Yeah you basically open the macro menu (can just type out /macros and hit enter) and then you select one of the 100 or so macro's. Select the typing area, input that info. Select the icon that was created (the one on the left in the big patch of 100 possible macros) and drag/drop it onto your hotbar (or however you place skills on PS3/4). You don't need to have Blunt Arrow on your hot bar anymore now that you have it in a macro.

That last point is a helpful thing to remember for cross-class abilities as well. As long as you have an ability selected in the abilities window you don't need to have it on your bar if it's in a macro.

You could make a macro that has all of your buffs in it like:
/ac "Buff 1" <me>
/ac "Buff 2" <me>
etc

And only place the one macro on your hot bar and not each individual skill in order to save space.