Update, Aug. 9, 2016: Analysis of the use of command syntax in the 1835 Doctrine and Covenants as well as in our current edition shows strong differences in command syntax relative to the Book of Mormon. The results tend to be closer to the King James Bible's usage, though there may be an influence from Book of Mormon language in the Doctrine and Covenants text, especially for the sections written prior to publication of the Book of Mormon.
The 1835 text has 40 instances of the verb "command" in some form directly governing one or more other verbs, with a total of 44
Finite forms are often in the layered structure, e.g., "I command him that he shall...." instead of the simple form, "I commanded him to ...." However, "that" plus a finite verb can also occur in a simple, non-layered form, as in "I have commanded that you should pretend to no other gift...."
A count of layered vs. simple format for command syntax in the 1835 Doctrine and Covenants gives 31
Of the 40 occurrences of "command" as a verb governing another verb, in 27 cases the command form was entirely simple, in 11 cases it was entirely layered, and in 2 cases a single instance of "command" was used with both forms. Thus, the verb "command" was used in layered forms 13 times (11 pure occurrences+ 2 mixed occurrences), and counting the mixed cases twice in the denominator, we get a rate of 13/42 = 31% for the rate at which the verb "command" is applied in layered formats. Similarly, the rate at which "command" is followed by finite verbs is 33%.
In tracking command syntax, I attempt to follow Carmack Stanford in identifying forms of the verb "command" that govern at least one other verb. Sometimes an instance of "command" governs two or more verbs, and in two cases the results are mixed, meaning, for example, that "command" governs both a finite verb and an infinitive, as in: "I command you, my servant Joseph, to repent [infinitive] and walk more uprightly before me, and yield to the persuasions of men no more; and that you be firm [finite form] in keeping the commandments...," which has one
The 1835 Doctrine and Covenants' first two occurrences of command syntax come from quoting Genesis 3 ("commanded that they should be brought unto Adam" and "The woman whom you gave me, and commanded that she should remain with me"). I exclude these from the statistics since they do not help us understand the language of Joseph Smith and the scriptures he created, but that exclusion has very minor impact on that statistics.
Our current printing of the Doctrine and Covenants is different in many ways, lacking the Lectures on Faith, having a variety of textual changes, and also having revelations given after the printing of the 1835 edition. Analysis of its command syntax shows the verb "command" in some form was used to govern one or more verbs 56 times, with a total of 60
The 56 instances of the verb "command" governing other verbs occur in purely simple forms 42 times, purely layered forms 11, and mixed forms 3 times. They govern only infinitives 41 times, only finite verbs 12 times, and mixed forms 3 times, showing a finite rate of 25.4%.
Though it may be a statistical fluke due to small sample size, the command syntax in the modern printing of the Doctrine and Covenants seems to show a high finite rate (over 50%) in the earliest sections recorded before the publication of the Book of Mormon. Sections 5 (the earliest occurrence of relevant command syntax) through 19 (recorded shortly before publication of the Book of Mormon) show 15 occurrences of finite form command syntax and 8 in the infinitive, for a finite rate of 65%, rather close to the Book of Mormon. After that, the finite syntax plummets.
If that observation is correct and if it has any significance, then one might speculate that during the days of preparing the Book of Mormon and its manuscripts, it may have been that at least this aspect of Book of Mormon language was fresh and strong in Joseph's mind, and subtly influenced other writings or dictation at this time. Following publication of the Book of Mormon, perhaps his own language became more controlling.
The question, of course, is whether Book of Mormon language was influencing Joseph, or whether it was entirely the other way around. If he was a prophet and was obtaining revelation to dictate the text of the Book of Mormon with a tightly controlled process, I can see the logic of a the language of the translation affecting him strongly during this period. On the other hand, one can assume it was just his natural language all along, affected by his desired to sound archaic and scriptural, and that those constraints gave us the language of the Book of Mormon, which then may have changed naturally as he matured. Or perhaps other hypotheses need to be explored.
As with the exploration of the subtle use of "did" in the Book of Mormon for past tense, and its general absence in the Doctrine and Covenants, this tentative and possibly error-prone examination of command syntax suggests that an appeal to Joseph's natural language and his desire to imitate the KJV fails to account for the high level of layered, finite command syntax in the Book of Mormon. However, the presence of high levels of finite syntax during the early days of the Doctrine and Covenants that overlapped the Book of Mormon translation and preparation process could suggest that such high levels do not necessarily require miraculous guidance. On the other hand, those trends could also be explained as a side effect of the miraculous guidance that gave Joseph the text to dictate to his scribes in the first place, which may have subtly but strongly influenced how he formulated command syntax when giving other scripture during that time. As always, further work is needed, and this present work may contain a variety of errors requiring revision. Your feedback is welcome.