I was looking at this last year (to avoid ATP-CTP cost).
The problem is that the T/R is typically completed at a 142 school. These can only offer specific approved courses. I was advised that they could conduct a PP with Type Rating, or an ATP, but not Commercial. The check-ride itself is to ATP standards anyway.
There may be schools that could do this, might be best to check with the FAA for what approvals are granted?
Otherwise, as stated above, ICAO commercial can go straight to ATP. It will cost more, but the simplicity and reliability of the route (for an experienced pilot) to train on current type for ATP-CTP then ATP with Type Rating is definitely recommended.