A good way to model quicksand sectors?

[Skwirl]

What's a good way to model "quicksand" sectors?

I imagine ACS is going to play a big part, as did other special sectors I use in my project, but before I go through that trouble, I want to know if there's "tried and true" methods, or something nice and modular so I can have like partial quicksand that could slow you down, or quicksand you can end up drowning in even if there's no real swimming used (where like in some oldschool platformers you'd have to repeatedly tap jump until you're completely out).

I've found threads that made comparisons to it, but not enough for me to understand a working model just yet, anyway.

[Caligari87]

Perhaps a pit with a "swimmable" [wiki]Transfer_Heights[/wiki] or [wiki]Sector_Set3dFloor[/wiki] over it, set friction higher and lower gravity. That's how I'd start anyway.