I have recently tried again and now I happily have both network cards working!!
Reading a little more about compat-wireless and its capabilities, I found out that the source code provides you with a script that lets you select the specific driver you need. As I knew which chipset I was working with, the script automatically generated a new makefile with the driver family I specified.
After that, I uninstalled bluetooth drivers that the package installed by itself, and finally recompiled the wl driver module for the integrated card. Fortunately, after all these steps, I have both network cards and bluetooth working perfectly in the 2.6.38 kernel.
Thanks for your help! I'm marking this thread as solved