im thinking of getting some type of oil pressure gauge for my car. i was just wondering about what is involved in hooking one up.

Well it depends on if you are going to use a mechanical or electric gauge. If you go with electric, then you'll have a sending unit under the hood that sends the signal to your gauge. If you go with mechanical, you'll have an oil line going into your car to the back of the gauge. Personally, I'm going to go with electric so I don't have oil coming into my car just in case anything were to ever go wrong. Please feel free to correct me if I am wrong in what I've heard about these gauges.

so if i go with electric one, where does that sending unit plug into?

I just installed on on my probe a couple weeks ago.
Real easy
the gauge should come with a new sending unit(mine did)
Find your stock one, unbolt it/unscrew it.
replace with new one.
run wire from guage to sending unit.
I used power from my CD player for all my Autometers and then grounded it at a good point inside the car.
after that, make sure everything works and is hidded, then mount.

On the celi the unit is to the right of the exhaust manifold, just below the valve cover.

does any company make small digital gauges that would fit under the cd player?