[Lazy]

I can't remember which one I used but it was definately a custom one.
That isn't the problem though, inorder to use something like a multi_manager which has upto 16 custom key/value pairs for the target entity and firing delay you need seperate structures/memory for each type of entity.
As far as I know all you get in quakec is the entvars_t structure unlike hl where you got pvPrivateData for classes, ect...

One idea would be to rip out quakec entirely and put a new native system in place but that makes it really tempting to use the HL system.
All the code is there but is unusable to anything but valve products so you'd have to re-create everything including porting over the basic entities from quakec.

But model support is the real killer here, everything else is possible to re-create.