It seems like the common case for wanting to install a kernel module source package is to build the module and then install it on the same box. Since the *-source package doesn't really depend on *-utils, why not add a Recommends line?
For example, ndiswrapper-source would Recommend ndiswrapper-util, while ndiswrapper-module-* would Depend on ndiswrapper-util still. (Similarly for alsa-*, and any other modules.) -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]