Building 2.4 modules outside the kernel tree

I'm having a bit of a hard time figuring out how to build a module for a
2.4 kernel outside the kernel tree....

I am following the book, Linux Device Drivers, which is written for 2.6
kernels, so I expect that things will be a bit different.

For 2.6 kernels, this works:

make -C /usr/src/linux-2.6.15.1  M=`pwd` modules

But I can't find an equivalent command for 2.4 kernels....

make -C /usr/local/src/linux24 M=`pwd` modules

Just builds all of the 2.4 modules, and not the one in `pwd`....

$M seems to be ignored... So how can I do this for 2.4 kernels?

--Yan