Is there some short-cut?
Run xconfig again, select the option as a module, and recompile. If the
tree hasn't been cleaned since you last built, it should only compile
that one module and not the entire kernel. When this is done you can
either reinstall the kernel or just copy the module in question into
/lib/modules/<kver>.
IIRC, the OP said he used kernel-package. If that is the case, add
"do_clean := NO" (without qoutes and on its own line) to the file
/etc/kernel-pkg.conf to ensure that the script does not run a clean by
default after it is finished building.