I read some hint that it could be done by slash command and each ability is assigned a number. My questions are what exactly is the slash command? And where I can find the table showing the number associated with that ability?
/alt activate ### is the command, as grovers said. You can look the AAs up here, and the macro command is listed in the Quick Facts box on the right of the pages of active AAs (ones that need to be pressed). Links: https://everquest.allakhazam.com/wiki/Category:EQ_Alternate_Advancement for list of AA catergories and class specific pages. or you can just type the AA name in the search box also, and do the wiki page of the same name.