I assume you are talking about one of the two hoses that go from the power steering pump, up to the top of the engine where they connect together via a short tube, then back down to a longer tube that connects to the steering rack. I've had to replace all 4 hoses in the two 2002 XG350's I own (his & hers). I would suggest you just replace both because, chances are, you will need to eventually. I'd also stay away from the slightly cheaper "dual" hose available on Ebay that does not come apart between the two hoses because installation is MUCH easier if you connect the lower end each hose first and then connect them on top as the last step.
1) remove as much power steering fluid as you can with a turkey baster.
2) remove hose from power steering pump from underneath car. This can be a real B**** because its so cramped. Hopefully you have the right wrench and its not too tight. Let the fluid drain.
3) disconnect the two hoses from each other from up on top. The hose to the power steering pump can come out now.
4) I found the 2nd hose to tube fitting to be impossible to get to, so I removed the other end of the tube from the power steering rack. Then the hose and tube can come out.
5) Move the tube to the new hose, re-install, and connect to rack
6) connect other hose to pump
7) From up top, connect hoses together and fasten to vehicle.
8) Fill power steering reservoir. Start and run car for just a second or 2
9) Fill power steering reservoir. Repeat 8 & 9 until fluid stays at or near full.
10) start car, turn steering wheel all the way to the right, all the way to the left, and back to center. Turn car off
11) top off power steering reservoir. Check for leaks. You should be done.