I just went through the similar leak (same spot) with my 01 non-S tiptronic trans. I also poured dye into the engine oil but the result was inconclusive. You can read my post here
http://986forum.com/forums/boxster-general-discussions/68587-one-engine-transmission-leaking-oil.html
Finally, this past weekend, I just replaced the engine oil & filter. Immediately, I can tell the leak is not from the transmission because the leaking fluid is clear & clean (like the oil I just poured in). This plus a few people from the forum believe it's likely an RMS leak made me feel more confident.
Since my car is 16 years old, and it costs an arm and a leg to fix this leak, I think I'll just put a pan underneath the car and watch the oil level. Hope this helps.