You'll need a diesel compression tester (NOT a gas engine compression tester!) plus an adapter that replaces a glowplug or fuel injector. I have a cheap one from Harbor Freight that came with a bunch of different adapters. I remember it being around $50.
I find it best to pull all injectors and so the engine spins with less resistance, and there's no chance of it actually starting. Screw in the injector-adapter, connect the compression tester and crank the engine until the needle stops climbing (about 10 cycles). Write down the number, relieve the pressure in the hose, move to the next cylinder and repeat. Pressure shouldn't deviate much between cylinders. Anything under about 350psi and it's going to be hard to start.... if it starts, doesn't burn oil or have too much blowby I wouldn't worry about it. Good luck!