These pants are some of the hardest of the TS quests to get! Two of the items are very easy to obtain (I forget which offhand), but the two that are dropped in SD and TS, respectively...insane. The mob that is needed in SD (sorry for forgetting the name, I gave up on these pants long ago and just got my military leggings) I have never seen up, nor have I known of anyone else to see him up, although I must assume he has been, just very rare and in among all the other varied aliens.
The one in TS, a vas ren oracle, is up often enough. The problem is that he spawns in the large alien area in the north of the zone, where you have to swim through a tunnel underwater in the sea, to get to. This is not so bad, but while the aliens in the main part of the zone are weak and do not add, this area is higher level and their agg radius is huge! Everything in that part of the zone is social and all will add on any pull. I grabbed one mob, pulled him to the wall and kited it along the wall...within a minute I had 6 mobs chasing me, all resistant and hitting hard! I barely escaped. If you wish to solo in this area, good luck. If you bring a group, you need to be tank heavy and high level or have damned good crowd control. This is a very nasty part of the zone.