Under the current TOS I think you could do it legally pretty effectively with a keypad & 4 keysticks tied to 5 PCs, VMs, or MDs (Multiseat Desktops).
I may try it but, even with the above being said (typed), if I do I likely won't risk my original main account with all my Collector's Editions as I don't trust Blizzard anymore... I would only use that account as a 6th account for a Mage for free water/food/portals & maybe for a main for Raids & dungeons with others (but not my own boxing team).