I can do this, however, you will need to code the dll. To add the new grunts... If you just edit the fgd file then yes, you will get them in the etities dropdown box, however when the entity is placed in the game it will not appear..
You see I did this with the oposing Force grunts and added there sequences and everything (because I have the latest Hammer {3.5})
but when placed in the map there was nothing because the dll is not edited with the new grunts. This task is very easy to handle, Just get a decompiled dll (sdk source) and copy the hgrunt files but rename them to swat, and edit the cpp and h files (etc) So that there is no "hgrunt.mdl" in it, instead "swat.mdl" Then compile it. and then edit the fgd file.
I would be happy to do this for you, however, I don't have anything to compile the dlls and stuff, thats why I am loking for help as well trying to get someone to add to the dll and compile.. but no luck.