I have found a way in which you can play with Neo Trinity Morpheus and more...
1. Firstly you have to open your enter the matrix folder, then open the "actors" folder (make a backup copy called "actors_backup").
2. Then you have to find all the Costumes for the original players...(e.g. "Ghost_Costume01.dcx" or "Niobe_Costume01.dcx").
3. Then find the player you want instead of Niobe or Ghost (e.g. "Neo.dcx") and copy that file to how many costumes there are for each player. (e.g. 5 Ghost Costumes = 5 "Neo.dcx" copies)
4. Then rename all the ".dcx" for the desired player (Neo.dcx) to the original player costumes (ghost_costumes01dcx).
5. So..."Neo.dcx" will be renamed to "Ghost_Costume01.dcx"...and so on...
6. After that load a game or start a new one and you wil be playing with a different player.
All the characters moves will remain the same...only the skin will be changed.
I have tried the following players and thry have worked for me: