I recently got a T/C Omega and I never feel comfortable shooting the V type rear sight that comes with it. I thought I would share what I learned about installing a peep, which for me is much easier to use in the field.
Wilimas sight company makes a rear peep that can be used on the Omega or Encore. got mine from Cabelas for $25-26. If you buy the one for the Encore, it works for the Omega too. It simply screws into the 2 holes on the back of the barrel just in front of the breech. This is further back than the factory sight is mounted, which is good for a peep. No drilling is required, works with existing holes.
However, the front fiberoptic sight that comes from the factory is too tall and even raising the peep as high as possible, you still hit too low. Turned out to be a simple solution. Called Thompson Center and they sent me out a shorter front fiberoptic sight free! Now shoots great.
Took me awhile to figure all this out, so hope this helps others who want to do the same thing.