I'm sure it is possible. I believe someone posted a WIP screenshot of Buccaneer Bay working in BF2 somewhere in the screenshot thread....
Primarily the init con and initlogic of the map needs to be merged to one file and some restructuring of how the objects zip files are organized. Since BF2 doesn't support the way BF2142/BFHeroes mounts the objects zip files. (they all need to be in one archive and not in the objects subfolder either. Perhaps you could mount them all separately. Just don't leave them in the objects subfolder)
Don't forget to change the kits and such. It may be possible to use the old pre closed beta meshes on the soldiers in BF2 if you un rem out the geometry lines in the soldier archive. But note that the animation system lacks 1p animations and also lacks the 1p arm mesh.
Though I have more experience porting this game to BF1942 and not BF2, so sorry that I can't be of more help. :P