In such situation You may use plain PRISM command (pick one best suitable there are couple variants of it)
At first draw a slab with the cutting You need...then save it to GDL - now You can analyse the script and put the veariables in place of values.
Alternatively draw 2 slabs one will be the base the socond will be cutting - then save to gdl...
now one of the prism You may change to CUTPOLY
But cutply have to be first...then the base and CUTEND after the base
Refer to the GDL manual for the proper syntax
You will have to add proper ROT before anyting
and DEL 1 (if one transformation like Rot is there)
Alternatively You may make Solid operation to the slabs You draw, than save it to GDL - than of course change the proper values to parematers.
Best Regards,
Piotr