I've never this and think it's actually against the rules. In the game in the Players Championship semis, Yorvit Torrealba is the starting catcher batting ninth for the Bats6. Dan Uggla was the starting DH, hitting 8th. In the top of the ninth, Mathis was substituted for Uggla, but put in at catcher, while Torrealba was switched to DH. I don't believe the DH spot can be moved in the lineup. You cannot start the game as a position player and be moved to DH.
Anyone ever seen this before?
http://onlinegames.strat-o-matic.com/game/348328/624