kernel conf.
 

how do you reconfigure the kernel?
for example to add support for a file system?

Quick answer

make xconfig
make dep
make clean
make bzImage
make modules
make modules_install
make install
lilo
reboot

Depending on your distro, the make install ; lilo ; reboot part may or may not work! You'd need to read up on lilo to make sure.

The other option is to read the documentation

http://www.tldp.org/HOWTO/Kernel-HOWTO/index.html

It is rather a long process and can leave you with a crippled machine!

Darren.