Biggest problem is usually getting the old rubber ones out, as they have a tendency to get quite comfortable in there !
If you don't have a press to move them... the normal method is to burn out the rubber bit with a blow torch.. the centre tube and rubber should all come out. (Don't breathe the smoke... it's nasty)
You will then be left with a tube in the panhard rod. You can carefully cut this with a hacksaw or similar device. Take the blade out, put it through the tube, and then reattach it to the saw. Cut a slot in the tube, being careful not to but into the actual panhard rod. This should give the tube sufficient slack to allow you to drive it out with a hammer / drift.
