Binary specific SLEIGH extensions

[sad-dev]

On windows binaries, int 0x29 (__fastfail) corresponds (in the context of the function) to a no-return. More generally, a user might want to specify the effects of certain PcodeOps which involve 'external' values e.g.

define pcodeop __fastfail;
:INT29 is vexMode=0 & byte=0xcd; byte=0x29  { __fastfail(); goto inst_start; }
:INT66 is vexMode=0 & byte=0xcd; byte=0x66  { intloc:4 = 0xDEADBEEF; call [intloc]; }

(how to modify int29 to noreturn is another thing i would love to know how to do in SLEIGH, if anyone has ideas)

What would be a good way to specify such binary specific sleigh extensions/overrides?