I've done exactly as suggested by the previous post, but it seems there's still something amiss. I'm afraid I am quite the newbie with Myth so sorry if I ask something obvious.
First of all, I am running KnoppMyth R5A16 on a pretty basic Athlon board.
I have a Technotrend DVB-C card and after inserting the stuff mentioned it seems to be detected at boot time.
When running capture card setup, however, I got the message "unable to open card #0" and "device or resource busy" which is kind of funny. Maybe my card was watching tv behind my back?

This I managed to solve by manually shutting down mythbackend and my card was then detected fine by Myth as ST STV 0297 DVB-C.
I've struggled through the rest of the setup somehow and even got my Finnish channel lists populated somehow. The problem is that when the setup is done and I get to the actual MythTV and select "Watch TV" I get a black screen for about 10 seconds and then Myth crashes me to the desktop. The output I get is as follows:
2005-06-20 12:19:10.752 New DB connection, total: 1
Total desktop width=1024, height=768, numscreens=1
2005-06-20 12:19:10.765 Using screen 0, 1024x768 at 0,0
2005-06-20 12:19:10.790 Switching to square mode (blue)
mythtv: could not connect to socket
mythtv: Connection refused
lirc_init failed for mythtv, see preceding messages
2005-06-20 12:19:11.155 Joystick disabled.
2005-06-20 12:19:11.271 New DB connection, total: 2
2005-06-20 12:19:11.301 Connecting to backend server:
212.226.129.45:6543 (try 1 of 1)
2005-06-20 12:19:11.309 Using protocol version 15
2005-06-20 12:19:11.348 Using protocol version 15
2005-06-20 12:19:16.491 taking too long to be allowed to read..
2005-06-20 12:19:21.493 taking too long to be allowed to read..
2005-06-20 12:19:26.494 taking too long to be allowed to read..
2005-06-20 12:19:26.494 Took more than 10 seconds to be allowed to read,
aborting.
Couldn't read file:
rbuf://212.226.129.45:6543/cache/cache/ringbuf1.nuv
2005-06-20 12:19:26.517 Changing from None to WatchingLiveTV
2005-06-20 12:19:26.517 Decoder not alive, and trying to play..
2005-06-20 12:19:27.506 RemoteFile::Read() failed in
RingBuffer::safe_read().
2005-06-20 12:19:27.715 RemoteFile::Read() failed in
RingBuffer::safe_read().
2005-06-20 12:19:27.924 RemoteFile::Read() failed in
RingBuffer::safe_read().
2005-06-20 12:19:28.133 RemoteFile::Read() failed in
RingBuffer::safe_read().
2005-06-20 12:19:28.342 RemoteFile::Read() failed in
RingBuffer::safe_read().
2005-06-20 12:19:28.504 Changing from None to None
2005-06-20 12:19:28.551 RemoteFile::Read() failed in
RingBuffer::safe_read().