Also for anyone who's annoyed at losing their class icon (like I was), you can add /micon # gearset in front, i.e:

/micon 3 gearset
/gearset change 3 2

If your 3rd gearset is your MNK, it would add the MNK class icon as the macro icon, and then change you to your monk gearset and add glamourplate 2. I know I used these all the time to switch classes so not having to wait to mouse over names or memorise where they're located helps. (It also works for DOL/DOH.)