If you want to get really creative, put him in the starter slot until the ball appears next to his name. Then, move him into the bullpen prior to the game. The ball will still appear next to him and he'll get the start, but you'll be able to lower his pitch count as low as you want. Then just move your next desired starter into the SP1 slot. It requires regular attention, but it has worked in instances where I made a trade involving the next game's starter and wanted to get him out after 5 pitches to reduce chances for an injury.