But I came across a program (for linux) that could change this, namely Tvheadend (http://www.lonelycoder.com). You can either download the .deb package and run dpkg -i package.name.deb or download the latest svn by doing
svn co svn://svn.lonelycoder.com/hts/trunk/tvheadend && cd tvheadend && ./configure && make
If you downloaded and extracted the .deb file instead, you will be prompted for user/passwd when installing, you should be able to find tvheadend in /etc/init.d/hts-tvheadend (use switch stop/start)
you can access the web user-interface by accessing http://127.0.0.1:9981 and setup the dvb-adapter and probe channels. Once all is set, go to your XBMC, and Add source > "htsp://127.0.0.1" (w/o "). If the webui found any channels, you should now be able to access those and enjoy tv function on your XBMC htpc
You can use the webui to schedule recordings, at the moment, you cannot record while using the program itself :/
For support, visit #hts at irc.freenode.net
edit: added -C switch to be able to skip user/password prompt, be sure to create a specific user in the ui to be admin instead of * tho.