emu10k1 driver can't find kernel sources

[Joel Konkle-Parker <jjk3@msstate.edu>]

I'm trying to compile the emu10k1 drivers from 
http://opensource.creative.com, but when I run 'make' for the first 
time, it tells me that it can't find /lib/modules/2.4.18-686/build, and 
therefore can't find the kernel sources.

I'm using kernel-image-2.4.18-686. How do I fix this without compiling 
my own kernel?

- Joel