The 1920 LDS edition changed “on him whom ye shall lay your hands” to “to him upon whom ye shall lay your hands”, although there is nothing particularly difficult about the original text here. A parallel use of the preposition on, at least on the surface, is found in the next verse:
Of course, upon is also possible:
Elsewhere in the text, there are two more occurrences involving on with the expression “to lay hands” (when referring to blessings or ordinations):
Thus either preposition, on or upon, will work here in Moroni 2:2.
Even so, the pronoun him can be interpreted as the indirect object for the final clause in the sentence, as if the text read “to him ... ye shall give the Holy Ghost”. This may have been the reason why the 1920 committee felt that the preposition before him should be to rather than on (another possibility would have been unto).
David Calabro points out (personal communication) that here in verse 2 the original text may have read as “him on whom ye shall lay your hands ye shall give the Holy Ghost” (that is, the earliest reading resulted from a switch in the word order, from him on to on him). But since the earliest reading here in Moroni 2:2 will work, despite its oddity, the critical text will restore that reading (namely, “on him whom ye shall lay your hands ye shall give the Holy Ghost”). There is no textual evidence from mix-ups in word order that would support either the 1920 reading or Calabro’s proposed emendation as the original reading.
We also briefly note that here in the printer’s manuscript Oliver Cowdery initially wrote the singular hand (“on him whom ye shall lay your hand”). Virtually immediately, he corrected hand to hands (there is no change in the level of ink flow for the inserted plural s). Elsewhere, the text has five instances of “to lay hands (up)on someone” that refer to blessing or ordaining someone. In fact, all five of these are listed above, with two of them occurring here in Moroni 2. The plural hands is also used when “to lay hands (up)on someone” refers to physically taking hold of someone (20 times). In the manuscripts, Oliver frequently mixed up the number of the noun hand (for some examples, see under Mosiah 16:1 and Alma 5:4). The critical text will maintain the plural hands here in Moroni 2:2.
Summary: Restore in Moroni 2:2 the original on him whom in “on him whom ye shall lay your hands”; there is nothing particularly difficult about this reading; the critical text will also maintain the plural hands in this clause.