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.

***NOTE***
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:
Neo.dcx
Morpheus_coat.dcx
Trinity_zen.dcx
AgentSmith.dcx
AgentThompson.dcx
AgentJackson.dcx
AgentJohnson.dcx
Seraph.dcx
Keymaker.dcx
Sparks.dcx

Enjoy!!!