The little rectangle of lights to the left of the gauge cluster.

Is there a way/procedure to light them all up temporarily?

On an old car I had there was a way to do that with a sequence of brake pumping and ignition fiddling.

Just as a check to ensure the bulbs are working.

its a 94

i know on a my 98 you can hold down the trip reset button with the key off and turn the key on while holding the button and it sweeps all the gauges and blinks all the lights. you could try that.

I doubt that will do anything since 94's use a mechanical trip and odometer.

Just test them individually if you have to.

The brake light should come on when the parking brake is engaged.

The part-time/full-time lights should come one when their respective modes are engaged (though the switch for this light often fails, so if it doesn't light up, the switch is the more likely reason).

The seatbelt light should light up when you start the vehicle without your seatbelt on.

The CEL should also light up with the key turned on (I assume; I haven't owned an OBD1 XJ)