[Nix-dev] Kernel headers

[Pjotr Prins]

I have a basic question. I have created a Kernel_headers expression for
2.6.18. How do I override the NIX build without changing:

   kernelHeaders = kernelHeaders_2_6_23;

to:

   kernelHeaders = kernelHeaders_2_6_18;

In other words, what switch to I pass nix-build/nix-env -i to
ascertain headers 2.6.18 without changing the default line in
all-packges.nix? I would like to keep the SVN tree generic.

Similarly, how do I create a 32-bits package on a 64-bits machine
(cross build). Can anyone just give a quick example? All the stuff I
try does not work. It could be me ;-).

Pj.