My '98 has cracked bushings on both upper and lower ball joints in the front. I have seen some information on replacing lower bj's, but nothing on the uppers.
Any suggestions or directions on these?

 

Upper ones are easier than the lower ones(but the bushes are more complicated), as you don't have to remove the spring for it.
I think you will do both in the same time, sometimes is difficult to remove the upper bolt due to the rust that is "welding" the bolt to the chassis.
Have a look on this topic HOW TO: Replace Front Upper Suspension Bushings (VIDEO) [FAQ] - Jaguar Forums - Jaguar Enthusiasts Forum