The problem is solved - I can now successfully build a working gpc (cross) compiler on Intel Mac OS X 10.5.2. The following items did the trick:
1) A sysctl-free patch for __enable_execute_stack (Thanks to Adriaan and Gale for helping on this one)
2) Using sed 4.1.4. instead of the Apple supplied version of sed (maybe it would help to add an sed check in mk-t-inc).
Peter --- peter.schorn@acm.org