Is it possible to do a interior thread in acme?
YES
Is it possible in lazyturn
NO as LT is for doing profiles and dosen't provide code for threading. You need to use the wizard.
Have look at Threading on the Lathe - Mach 3 write up as multi start treading is talked about. You really need a good cnc lathe system.
You can use alternate flank cutting to cut acme threads, 5 start ....i would not even attempt it here on the outside yet alone on the inside.
Frankly farm it out unless you have tested and done that kind of work.
FWIW,
RICH