What an interesting question! I've just made a temporary switch from being a boxer back to a solo-boxer for the time being.
On my protadin, no changes necessary to solo-box...tanking while boxing vs tanking while soloing in instances is just the same thing 
On my holy priest, well, I had set my macros up anticipating some solo play. They sorta look like this (going from memory):
Helpful (healing) spells:
Code:
/cast [target=mouseover,nodead,noharm,exists] Renew
/cast [target=target,nodead,noharm,exists] Renew
/cast [target=party1,nodead,noharm,exists] Renew
/cast [target=player] Renew
Offense spells:
Code:
/cast [target=party1target,harm,exists,nodead] Shadow Word: Pain
/cast [target=target,nodead,harm,exists] Shadow Word: Pain
So, my healing spells, by default will try to cast on my mouseover target (I heal with Grid and mouseover the target I want to heal). Otherwise, it will try to cast on my current target, if they're friendly, exist, and aren't dead. If none of that is true (ie I have a hostile selected), then it will default to casting on the party leader (usually the tank...however if I'm in a group where the tank isn't the leader I make a quick change to the macro). And the final line, for when I'm soloing, will just cast the healing spell on myself.
Offense spells, by default will try to assist the party leader (again usually the tank). If that target is not selected or hostile, then it will cast on my current target, provided it's hostile.
By setting up your macros in such a fashion, you don't have to worry about swapping/changing anything when you switch between soloing and boxing.
Connect With Us