Jamien is correct, however in case you are still wondering; the problem with your original macro was that the mod condition was seperate from the status conditions.

Corrected:
#showtooltip
/cast [combat,nomounted,mod:alt] Ghost Wolf
/cast [nostance,nocombat,noflyable] Swift Brewfest Ram
/cast [nostance,nocombat,noflyable,mod:ctrl] Tawney Windrider
/dismount [mounted]
/cancelform [stance]

Having /cast [combat,nomounted ][mod:alt] Ghost Wolf means it will check for combat and mount status, and only if those are false will it check for the alt key.