Get the spikes. I'm not sure there's any 'trick' that's learnable without growing up there.

Essentially it's about walking without ever putting your feet down such that they apply lateral force to the ground, however. Do that right, and it doesn't matter how slippery it is.

...and then you also can't apply force, so you can't walk. The hard part is to automatically test the ground you're standing on, ramping up the force fast enough to make progress, without thereby slipping. It's so automatic, I can't explain how or why it works. I suspect it's getting done in the spinal column, even.

A quick workaround is to buy some spikes for your shoes.

If you are in Scandinavia most outdoor and sport shops have them.

Just remember to take then off then you go inside =)