In my opinion, it is both possible and legal to do Crossover Circulate from the above-mentioned formations. However, in practice, it is not done. The offical Callerlab definition of Crossover Circulate restricts the call by saying "From General Lines Only", and then proceeds to describe the call in terms of a 4-dancer Circulate path.

However, it has been my experience that at Challenge, Crossover Circulate is generalized to be a "as one movement Circulate and Half Sashay". Doing a Crossover Circulate from T-Bones is not uncommon. For example, from a Squared Set: Heads Pair Off; Touch 1/4, Boys Roll; all Crossover Circulate. The Boys are expected to Circulate and Half Sashay, and NOT do a Circulate within their 4-dancer (Distorted Box) Circulate path.

The phrase "ends become centers and centers become ends", which only works from Parallel Lines, is only a teaching aid.

Ceder Chest Definition of Crossover Circulate