I'd assume so, that's the only way I can think to do it though
That being said, it's been done before and the codes aren't that large so I'm at a loss
EDIT:
I'm actually coming at this from the wrong point of view. I'm realizing now that if you make a play-as code in this way, then you have to have the person you're trying to play as in your party at all times or the area doesn't load. Back to the drawing board.
If I have create a code to play as a character using ps2dis the character is DMA (meaning I can only play it in the area that I dumped the data in)
If I wanted to create a similar code to play as a character, but have it be un-DMA, how would I do so? I know it's possible, but I also know that it's a ton of work.
I am guessing you would have to do something along the lines of: dump data for the character I am hacking in every area in the game and make a code using ps2dis for every area?