I've run t3 twice, once on a lean bulking cycle (didnt work like I thought it would) and this summer on a cutting cycle. You ramp up and down on it. Start with 25mcg for 4 days, then 50mcg for 4 days then 75. I stopped there and ran that until the last week where I ramped back down. I ran it for 6 weeks along with clen and dropped about 3lbs of body fat a week while adding at least a little muscle each week (being on a prop tren cycle as well).
Here, read this thread...
http://forums.steroid.com/showthread.php?t=137526
BTW, why not just run it with your tren and prop? What the heck kind of cycle are you running? It sounds all over the place from your vague descriptions