You can /useitem by name, and /disc by name but /cast is forced to be numerical. How much nicer would macros be if spells didn't have to be in the correct gem slot to work the way you want? /Cast Divine Intervention vs /Cast 4 and DI has to ALWAYS be in that gem or else who knows what you'll cast.
Remember this is Everquest. Be thankful we don't have to type the spell id in binary! For my SK, casting terror would be /cast 1110011011100011