I use my enlarger for a light source. That way I can use VC paper and adjust the contrast, and also use the lens to control the length of the exposure, so I can dodge and burn. (yes, it can be done) No neg in the carrier (of course) and the lens is set out of focus.
The first ones i did with a piece of glass over foam. Later I got a proper contact frame.
Eventually I ran up against Newtons rings (only when using Polywarmtome)
I sand blasted the glass on the negative side, and it solved the problem.
The hardest part is getting used to how simple it is. If you are doing silver, after your technique is down you will tend to compare all other silver prints to contact prints. There is truly nothing else like an 8x10 contact print. One of mine is at a local camera shop that supports LF. Of course they sell digi too (the owners do it so support their habit)
When "normal" people see it they are full of questions, almost always asking what camera and printer, while glancing furtively over at the D-what-evers and ink sprayers. The look on their faces when the shop owner points to the wooden 'Dorf in the corner and tells them it is hand done in a darkroom with a negative and a piece of glass is truly priceless. I could watch it every day.
If you have a 4x5 enlarger do you just remove the enlarging lens and turn on the bulb? I'm just trying to figure out how to the get the right amount of light across the negative.