How to make nvidia-kmod source package build an akmod package

I'm getting a sound card that requires a newer version of the kernel than F14 provides. (I need 2.6.38) I was able to build and install a F15 pretty easily and after a bit of poking around was able to manually make the nvidia-kmod package build for the F15 kernel by overriding the kernel lists: rpmbuild --define='kernels $(uname -r)' -bb... I still don't completely understand how the newest/current kernel version files interact but I would really like to get an akmod package built so I don't have to manually roll the kmod package every time I update the kernel. What's the secret to that? I tried commenting out the buildforkernels macro but that didn't seem to do it, presumably since it's still using the kernel versions in the "buildsys-build-rpmfusion-kerneldevpkgs-..." package. BTW, the new 270.41.06 drivers are working well on my GTS450.. Thanks, Richard