Yep, it's a threaded collar that is used over the strut, and the spring sits on it. So you turn the collar and the car either lowers or raises. And it uses the Eibach E.R.S. system, which Eibach uses a standard spring size and they change the spring rates. So, if you want a stiffer ride, you can change out the springs with stiffer E.R.S. system springs without the hassle have having a different sized spring.
The Tockicos on the MP3 can't really handle a sever drop, not more than 1.5" for all that long or they will fail. I heard the Mazdaspeed adjustable struts from Corksport can handle over 3" drops.
If you want a solid set-up for adjustable coil-overs, I would go to AWR Racing. They developed one of the Speedvision World Challenge Proteges. Good quality stuff.