I wanted to passthrough a dual tuner TV card (Hauppauge WinTV Nova-T-500) to an openVz container in order to use tvHeadEnd. The procedure should be the same for any PCI device.
First, identify the device you want to passthrough:
tree /dev/dvb/
This shows the device nodes under /dev/dvb/. Then mount the host device into the container by editing the container configuration file (/etc/vz/conf/CT_ID.conf) and adding:
DEVICES="c:212:*:rw"
Replace 212 with the major device number of your device (visible with ls -l /dev/dvb/…). After a restart of the container, the device should be accessible from within it.
You can verify with:
ls -l /dev/dvb/
Enjoy!