To expand on my previous post. Many distros don't install the source code unless you are building a development box. Since these distros don't install the source, some of the necessary kernel building programs also do not get installed. Make sure you have actually installed the sourcecode. From what you posted it doesn't look like you did.
-----Original Message----- From: Brian Densmore
/usr/src/linux should point you to the proper directory. First you will have to install the sourcecode.
-----Original Message----- From: Ben Coffman
where can I modify the kernel at...I looked under ../src/.. but could not find anything. Any suggestions.