Upgrading to CNC

It would be nice is someone would post a sketch or two and a list of
what is required to upgrade a standard knee mill to 3 or 4 axis CNC
milling controlled by a PC.

All the info I've seen posted so far and the web sites I've been
"directed" to seem to cover what's available and what the prices are.

With a good sketch and a list of required components, I'd know what
to go comparison shopping for.

Smoke