Re: How to add a new model...
Man, you're way off.
First: does your model have the correct helpers? (check
this guide.)
Second: if it does, you have to import your model in the graphics. big, not in the game.bin...
And for the record; if I were you I would start with just replacing the model of one of the crossbows from the game. Making a complete new entry with all cdefs and such will only be interesting if the model actually functions as it should (read: doesn't crash the game!).
[edit]
One more thing: don't double post. Be patient.
[edit2]
As for making a new cdef or OBJECT entry: Check
this guide. The guide refers to a CChestDef, but it is the same for an OBJECT or any CDef entry.