Can kbuild execute non-kbuild makefiles?
 

I'm trying to learn the gentle art of building a system on this suse 9.1 rig, which employs a 2.6.4-52-default kernel. The modem for this rig is a (soft) Modem Blaster USB variety, based on an ST7554 chip. The modem is working, but I have to install the drivers from package sources manually after every kernel build. I've created a symbol called CONFIG_USB_SMARTMODEM, which seems to be defined in '.config' as expected after 'make menuconfig'.
I added subdirectories "modem/slmodem-2.9.6" under "drivers/usb", which contains the subdirctories and files needed to get the modem working. The modem driver files are built using conventional sources and Makefiles and not the kbuild "obj-$(CONFIG_XXX) += xxx.o" conventions. The modem Makefiles are written to generate modules which are copied to the standard "lib/modules/<kernel-version>" directory. The Makefiles also generate a daemon which is copied to "usr/sbin", copies a script to the "etc/init.d" directory, and does a few other things.
I added "obj-$(CONFIG_USB_SMARTMODEM) += modem/slmodem-2.9.6/" to the (kbuild) Makefile in the "drivers/usb" directory, to give kbuild a way to get to "modem/slmodem-2.9.6" where, I hoped, kbuild would execute the Makefile. No luck there. Adding "obj-$(CONFIG_XXX) += xxx.o" in the Makefiles in the subdirectories will build and install modules OK, but the daemon, scripts, and other item operations are apparently ignored.

Is there a way for kbuild to install the modem components by executing the unmodified Makefiles that came with the modem? Would it be more appropriate to use a shell script to install the modem after kbuild has run?