I believe there is a different ruling for ASA under the Americans with Disabilities Act. I have no idea what their requirements are but I know it is possible.
It becomes the choice of the ADA player - defense only, offense only, or play both defense and offense. If they play offense only, then the team is using him as their one EP (or one EP for that gender if they're playing coed). If they play defense only, then the team utilizes the DP/FLEX rule from the fast pitch side.
However, anytime the ADA player bats, they are allowed a courtesy runner, which can be anyone from the bench. That player's spot in the line-up is not bound by the "one courtesy runner per inning" restriction, which is to say that that one spot can have unlimited courtesy runners.
If a player qualifies under the ADA, it must be announced prior to the game.