Do you have a mill/turn post? Are you writing the mill and turn on seperate files?
Unless you have a mill/turn post, MD, CD (or can write one), this could be challenging trying to do in the same file
If you're only trying to get the turn work through posting, this might now be that bad. If you're only on a Lathe seat, would be just a matter of writing the "A-90." as a hard code or through the use of switches built in MI/MR.
Might be able to get it recognize A angle by toolplanes but again, I'm thinking that a lathe post may not support that.
It's just a part..... cutter still goes round and round....