How to build a kernel
Start by getting the kernel source. Unpack the source tarball in /usr/src and make a symlink from /usr/src/linux pointing to the newly created source directory /usr/src/linux-x.y.zz.
Configure the kernel using make xconfig or make menuconfig.
Now, the old way to do it is to run
make dep && make clean && make bzImage && make modules && make modules_install
The newly created kernel (bzImage) has to be copied to /boot; also create a symlink in the root:
cp /usr/src/linux/arch/i386/boot/bzImage /boot/vmlinuz-x.y.zz ln -s /boot/vmlinuz-x.y.zz /vmlinuz
After this, check your /etc/lilo.conf and run lilo.
The new way to do all this is using the "kernel-package"-package.
Then, all you have to do after the kernel configuration is:
make-kpkg kernel_image
You can use the option --append-to-version=.yymmdd to create a unique kernel name in order to prevent conflicts.
This command creates a .deb file in /usr/src. Use dpkg to install this file:
dpkg -i kernel-image-x.y.zz_10.00.Custom_i386.deb
You will be asked if you want to create a boot disk and if you want to run lilo. Make sure your /etc/lilo.conf is up-to-date and run lilo.
The final step is to reboot the system.
For more details check out the info at http://newbiedoc.sourceforge.net/system/kernel-pkg.html