I don't think we can executing a TI-Basic program without make an interpreter in axe.

But we can easy change bytes of calculator's variables (pic, GDB, appvar, Str,...)
:getcalc("appvarA",1)->A
:.I create 1 byte in my appvar "A"
:Copy(8,A,1)
:.I copy number 8 in the only byte of my appvar

First of all, if you do a getcalc with a real variable you should always subtract 2 from the pointer since reals don't have size bytes in front; the size is ALWAYS 9 bytes.

GetCalc("varA",9)-2->A
Secondly, real numbers are floats, not integers, you have to manipulate them with float{} like this:

float{A}->B
8->float{A}
Running BASIC programs sounds like it could be done with a bcall, but I don't know of any.

DCS will let you run any DCS compatible program (BASIC included) and return to your program. I don't know how nice this will play with AXE programs though due to storage location of variables an such.

(Yes I do know, it's worth it though :p)
Well then they can't run it. But right now that's the best method for ease of programming. Although maybe AXE should have a RunProg command/routine too :p