Has anyone tried custom sleeve coilovers?

I have seen it done before in the past, essentially the strut is modified, or the sleeve simply sits on part of the stock strut as far as I understand. A set like these:

Adjustable Sleeve Coilovers - Suspension - Skunk2 Store

...are more what I am referring to.

Edit: I do have a set of skunk sleeve coilovers I can get for free so wanted to see if this has been tried.