I finally figured out how to get my Pinnacle PCTV (aka Mirovideo PCTV) BT848 card work in knoppix, and it was the detection routine that screwed it up.

I found that this card will lock up when launching scantv without first launching xawtv. (On other linuxes as well!) Apparently the card is not in an initialized state and scantv sends it a command to change the frequency which causes the computer to hard lockup. So to get the card to work I have to:
modprobe bttv card=39 tuner=6
xawtv (change to ntsc + us-bcast) and exit
then
scantv

And it will work. Even though scantv asks for the region and frequency mode it doesn't seem to work. Running xawtv fixes it. If I do the knoppix detection routine, it will start to scan channels and hard lock the system.

Well I hope this helps others who may have had problems with their tv card.