Hey Austin! Long time no hear.
You need the in beta test Sailfish 4.4 / 7.4 and RepG 40r16 in order to use the M322. Or, in place of RepG 40r16, Henry Thomas' GPX which also has a meta language for doing fun stuff like interjecting a pause @ Zpos and then knowing that the filament thereafter will have a different diameter.
To find out about the in-beta Sailfish and RepG, see the announcements at the jetty-firmware group at http://groups.google.comgroups.google.com. (You'll need to join to search/see postings.)
As to the format of the M322 (after you have RepG 40r16), to pause at Z=zzz.zz, use the mcode