I have a enemy TL with Omega Leader,

I roll attack dice from a Colonel Vessery attack.

I aquire a TL from Col. Ability.

I spend TL to reRoll bad dice,....

Now do I aquire another TL from the reRoll?

No. Rolls and rerolls are separate things. Vessery's ability cannot trigger during the modification step.

The answer to this question is found on page 21 of the FAQ.

Thank you

Fun fact that was brought to my attention during World's stream: If a ship is locked by a friendly ship by way of M9-G8, Vess gets a target lock when attacking that ship.