is the install the same as install on a newer model XJ? if not then what is the difference? and how do i do it?

The power steering pump is the tensioner. You need to loosen the bolts for the pump, then there is a tension bolt underneath the pump that will loosen the belt.

And, DO NOT pry on the pump housing.

so to put on serp belt to an 89 is the same as putting one on a 98?

No.

No

got a picture of the tensioning bolt thats under the pump?

Big fat arrow on the lower right.