Why are you modprobing an .so file! They're equivalent (roughly) to windows dll's, not to device drivers! Linux device drivers are .ko files, found in /lib/modules/kernel-version, and there isn't one named libbluetooth!

Anyway, if you have a different version of libbluetooth installed (my gentoo box had libbluetooth.so.1), simply create a symlink to that file - something like the following, as root on your Myth box "ln -s /usr/lib/libbluetooth.so.1 /usr/lib/libbluetooth.so.2"

It's possible the older lib may not have all the functions of the newer, so that's generally not the best idea, but if you're only using wlan anyway, it shouldn't be a big deal. If you ever do go to bluetooth, it could come back to bite you - could be a long and frustrating search for that link you created - speaking from experience here!