Cross-compilation problems

Hi,

I am trying to cross-compile LiS-2.18 for ppc using gcc-3.2.2. The 
ppc kernel version is 2.6.8.1. There are 2 problems:

1) The ppc cross-compiler does not know the 
-mpreferred-stack-boundary=2 option.

2)  When at some stage in the build process the 
modules/Makefile.modpost gets invoked, it is not aware that we are 
cross-compiling and uses the native compiler instead of the 
cross-compiler.

I could overcome both problems for now with quick-and-dirty hacks. 
What would be the correct way to solve them?

Any hints are appreciated!

Best regards,
Christoph