Howtoforge posted a guide about building Kernel modules with Module-Assistant on Debian Lenny
>> Building Kernel Modules With Module-Assistant On Debian Lenny
module-assistant is a tool for building Debian kernel modules from source, without having to rebuild the whole kernel. It fetches module-source packages that have been prepared for the Debian distribution via apt and produces .deb packages. This tutorial shows how to use module-assistant in command-line mode and in interactive mode.
>> Building Kernel Modules With Module-Assistant On Debian Lenny