[Vala] how to specify C toolchain to valac?

[Nigel Griffin <ngriffin vuze com>]

Hi,

Environment: Ubuntu 10.04 x86_64

Is there a way to specify to valac what C compiler (and C toolchain in general) to use?  I'm attempting to 
cross compile a program written in vala (which, I presume, only requires that the generated C code is cross 
compiled).

So far, it seems that my only options are:

1) add the location of the cross compiler to my PATH so that it always finds the cross compiler gcc first
2) Hand edit makefiles and set the toolchain there

If anyone has experience here, any suggestions on how best to proceed would be greatly appreciated.  Ideally, 
I would prefer to tell valac directly what toolchain to use.

-Nigel Griffin