On the Thai side there is an office marked for car paper work and I was directed there. I just never went in. So, I assume that the rules haven't changed, but I don't think many people bother going there. Everybody seemed to be just driving through.
On the Malay side there is an office clearly marked "ICP". I was directed there when I asked. They sent me to the insurance office first, where they also made up the black licence plate stickers and applied them. There is a checkpoint south of the town, but they were not interested in me.
Personally, I would not want to ride without insurance. Once you have that the ICP is free and quick, so there is no reason not to get one.
I crossed back at Sungai Kolok. Thai immigration was a pain. Had to queue just to get an arrival card, then queue again at the same window to get processed. Seemed to take forever and the officer was unfriendly, telling me off for not having filled in the departure portion of the arrival card. Well, I wasn't departing, was I?
Again, nobody was interested in the bike. There is a check point on exit, but I followed the bike taxis leaving through the entrance side, so no check point for me.
Unrelated, but part of the trip: I caught a nasty bug in Malaysia and my friend took me to hospital. Had to rest for 2 days, so decided to be lazy and take the train in Thailand. I think that was a good decision, despite the fridge-like temps inside.
Cheers,
Peter.