mh, it depends a little on the distribution, we at Slackware have a very good tutorial from AlienBob http://alien.slackbook.org/dokuwiki/...kernelbuilding
With many distributions you'll have to install the kernelsources before you can build a new kernel.
I use to build my kernel as a normal user in my homedirectory and afterwards install it as root. In short: copy the kernelsources to your home-directory (or load it down from kernel.org).
copy the .config file into the source-directory, then execute
there you go to "Device-Drivers"->"Block-Devices" and select the floppy-support. exit menuconfig with saving, then build the kernel
For the installation please look into the manuals for your distribution.