Hey guys, answered my own question. These things are stored as # variables. I found the Mach 4 Scripting Manual today in the manuals section where the Mach 4 is downloaded , which seems to be new unless I missed it previously.
2134 stores last feed rate
4001 stores G00 or G01 and results as 00 or 10
4003 stores G90 or G91 and results as 910 or 900
How to set variables (excerpt):
local CurFeed = mc.mcCntlGetPoundVar(inst, 2134)
local CurFeedMode = mc.mcCntlGetPoundVar(inst, 4001)
local CurAbsMode = mc.mcCntlGetPoundVar(inst, 4003)