Oh, how much fun I've had in the past with tie rod ends! In the situation you describe (where the end just torns freely with the nut) I've used a large hammer (5lb short sledge) to gently tap it down onto its seat, then firmly hold it down while trying to loosen the nut. Lots of PB Blaster and some heat (not at the same time unless you like to BBQ your car) help too. In one case I had to purchase a nut breaker (crosses legs) from Sears and split the nut off the tie rod end. Tie rod ends are relatively cheap and you're likely to rip the boot so I'd plan on just replacing it anyway.
Good luck,
Scott
