The shrader valve is near the front of the fuel rail, kind of like a tire valve.
You can use a jumper to the Diagnostic connect pin D-6 orange wire. Pretty much a straight shot to the fuel pump (through a couple of splices).
Or you can jump the 30 pin and the 87 pin under your fuel pump relay. This is kind of dangerous, if you go pocking around and jump the wrong pins bad things can happen. The pin numbers are usually embossed in the bottom of the relay.
I always use a fused jumper just in case. A little extra effort can save you a heap of trouble. In line fuse holders are cheap.
Jumping the fuel pump is good in two ways, it tests the pump and it purges the old fuel out of the fuel rail and fuel lines. Better to flush the junk back into the tank through the return line than into your injectors. The fuel coming out of the tank goes through a filter.
The last time I tried to start a XJ that had been sitting for a long time the pump didn't work. A few raps on front of the tank with a rubber mallet got it going again. It just needed a little nudge. Been working fine ever since.
If the pump isn't working don't leave the power jumper wire on there very long, if the pump isn't turning the windings can overheat and fail.