It takes more than a geom to make a working hair. You should start by cloning a game hair that's similar in length, etc, then you can use s4pe or CAS Tools to replace the lod0 mesh with yours. Most likely you'll have to also work with the textures. And at some point you'll have to do meshes for the other lods.
If you look here in the tutorials listing under meshing, there's a tutorial specifically on converting TS3 hair to TS4.