Most of the gm commands are stored in a txt file called STRRES.TXT which is in the Setup directory. Did you add yourself to the ADMIN.TXT doc for a start ??
Horses and pet rest :-
The command in CMLIST.DAT (client side) has to match what you have in strres file for them to work, forget the horse window, press Ctrl + M for horse and Ctrl + a for pet rest.