Well, it depends on what you are casting. I specced Arcane on my mages and use Arcane Missiles as my primary DPS. When you cast Arcane Missiles, it channels and breaks /follow so they will stand there after casting is complete. You could have other spells done after the initial cast. If you are worried about aggro, then you can downgrade to Rank 1.

Of course you have to reset the follow command once you are done. It started out as a pain but I find it very useful for doing just what you said.

Hope that was useful.

/goodluck