After i compiled and installed 2.6.4 on current slackware, i got some errors in the boot process, I dont know if anyone else has seen this error message, and im not sure why i got one (i compiled all my modules, opting to load none) Several "FATAL: Cannot open /lib/modules/2.6.4" and errors associated with that one popped up during my bootup (one set after clock sync, another after the 3c59x load)

since the kernel compilation didnt create that directory or the files that something is looking for, i created some empty ones to satiate it. it stopped complaining.

could this become a problem later?

As you didn't compile any driver as module this shouldn't lead to any problem.
Your method is smart, but rather unusual.
I'd suggest you look at your /etc/rc.d/rc.modules and then comment occourencies of the modules that cannot be loaded by i.e.
#/sbin/modprobe agpgart
or whatever you want.
Ciao

ahha, thanks, it was the "if there are new modules, add them to the list" script that was giving me the error, everything else was already commented out, thank you