I don't play HL anymore, but when I did, I found scheduling scrims to be a poor experience. Teams have to schedule a week or two in advance, then most of the time, scrims don't start on time anyway. It felt like a big waste of time to me. Gathering up your 9 players on a day they can all play then finding a scrim with another team who did the same thing would probably be faster. I don't think this is the issue in plat as much, but gold and below has poor scheduling, or teams flake all of a sudden, or they have to do last minute 3-4 ringer games, which doesn't help anybody get better.

Is there an IRC channel for finding HL scrims specifically? Would there be a problem with setting one up?

I know there are still people searching for scrims on occasion in the #tf2scrim channel, but I think separating them like the way pugna and mix are seperated might work better. (Of course there's no problem with people advertising for scrims in #tf2scrim, but I think people are hesitant to use it because it's largely based towards sixes)