I recommend you to read the manufacturer manul, they typically explain what to do.
However, I think that at least you shold test the following:
1) CTR, inject 1 A and the reading on the relay screen should match according to CTR
2) Test all the functions you have enabled and each one of them should close or open the relay contacts, as well as turn on the leds on the relay' screen and also an event on relay memory should be recorded.
If you are in the USA, you need to follow NERC guidelines. If there is a previous set of test results test what has been tested in the past, thus establishing a protocol. GE has a commissioning checklist in the manual, if you choose to follow their guidelines. Whatever you do, be consistent! Make sure your test equipment is calibrated and traceable.
As mentioned above, test all analog inputs (voltage and current). Test all contacts for proper operation.
As far as what equipment you need, at least a source with 2 currents (dif), voltage, variable phase angle and frequency. It also needs to have a timer. You will also likely need the GE SW which is free and available on GE Multilin website. You can rent test equipment, or if this is beyond what you want to invest, hire a qualified service company.
