Just a couple of thoughts on this:
1) When you remove the 1/4"SE from the existing cable, don't cut it at the plug. Cut it so it has about 12 inches of cable left attached to it. Then attach a 4pin female XLR to the other end to form an adapter. Then attach a 4pin male XLR to the main cable from the phones for direct connect in balanced mode. The main cable on the T1s is long enough that losing 12 inches is no big deal, you don't have to reterminate the SE connector, you don't have to buy any other cable, and the main cable and the adapter cable match.
2) I'm pretty sure that the stock cable used on the T1s is Litz cable. soldering it requires special tools and knowledge (e.g., a solder pot or extremely hot iron, correct flux, etc.). If you have not worked with Litz wire type cables before, it may be worth paying someone with the knowledge to do it for you.
3) Connecting the ground (shield) through the XLR case is not necessary and in some cases may degrade the sound slightly.
4) Using a 4 pin XLR for headphones (i.e., on the output) is not a typical application of the 4 pin XLR so "standards" vary. My suspicion is that finding a mass-produced 4 pin XLR to SE adapter will be rare. Wire the 4 pin male XLR to the headphone cabls appropriately for the amp you are using, and then adjust the adapter wiring to suit.
-Jeff