Bear with me, going entirely on memory in my head on this and a few external only pictures of my old gun.
CA33 MP5K Stock Mod.
Either brand of MP5K folding stock, from TM or CA will fit.
Remove the full stock from the CA33E, and disconnect the battery wires.
The stock, an stock mount, there is two screws inside there, undo them and seperate the stock and the metal mount for it.
In the mount, notice the rectangular shaped hole where the battery wire goes through.
Take note of the ledges around it in there, they are approx 1cm or so in length on all sides. Will return to this later.
Now you need a PDW stock, CA or TM works. On the stock, there is the side has the part the two body pin's on the mp5k go through. unscrew this and remove it from the stock.
The metal form that the stock is attached too, drill two holes in it, that are approx 2-3cm's apart.
Drill them vertically, so when you've shouldered the gun, one hole is near the top of receiver, an one is on the bottom side. Now leave the PDW stock.
Now you will need some sheet metal, or any sort. Steel is best for this, stainless if you have it even better.
Here is a template for what you need the sheet metal for.
It is a metal plate, that goes in your CA33's stock mount, the metal part that you took off. See how the flaps sticking out will be cut to fit the ledges in the mount I mentioned before. The one I made was only about 1-2mm's in thickness.
After you cut that out, an drill two holes in the same place you drilled them through the PDW stock's plate, run two bolts through there with washers on em and tighten it all up.
Use some loc-tite to keep it on there for long time.
There ya go, PDW stock on CA33.
As for the wires, you can run them up along into the front of the gun and house a battery there or drill a 3 hole for wires to run through out the stock and use a battery pouch/sling/ect.
I'd done both methods. 3rd hole is easiest.