In the original manuscript, Oliver Cowdery initially wrote glutting by; then with the same level of ink flow, he crossed out the by and supralinearly inserted the preposition in. The preposition in was edited to on in the 1920 LDS edition. (This last change is not a typo since it is marked in the 1920 committee copy.) The preposition on is nearly the same as the preposition upon used with the verb glut in the next verse: “we do not glut ourselves upon the labors of this people” (Alma 30:32). This subsequent example of “to glut upon” suggests that the committee for the 1920 edition could have selected upon instead of on as the emendation for Alma 30:31.
Elsewhere in the text, the verb glut takes the preposition with, and the second of these occurs in Alma 30:
Examples from the Oxford English Dictionary under the verb glut show that this verb normally takes the preposition with (27 times), but there are examples (some archaic) of other prepositions:
on 4 times
in 2 times
upon 2 times
for 1 time
The two OED citations with the preposition in show that the preposition in was possible in Early Modern English (here I retain the original accidentals):
The critical text will restore the unexpected preposition in here in Alma 30:31.
Summary: Restore in Alma 30:31 the original preposition in: “for the sake of glutting in the labors of the people”.