The two relevant things you need to know are:
- /useitem <slot> [subindex]
- /pause #, <command>
Combining the two you can bind up to 5 clickies to the same social button.
Example #1: an illusion with a 3 second cast time, a shrink click with 0.5sec cast time, in the first, and fourth slot of your second bag:
/pause 30, /useitem 24 0 [cast illusion]
/target <myname> [target self]
/pause 5, /useitem 24 3 [shrink once]
/useitem 24 3 [shrink again, no need for pause since its last line]
Example #2: Mana pool click (waist, 0.5sec), Mana regen click (third bag slot 1, 0.5sec), summon your familiar (second bag slot 5, 5sec), then get rid of the visible pet leaving the buff effect active:
/pause 5, /useitem 20
/pause 5, /useitem 25 0
/pause 50, /useitem 24 4
/pet get lost