Don't ask me, I ballsed it up
Just come in from th garage where I#m in the midst of rewiring them...
I hear K5s might have a spare live terminal on the fusebox, don't know if this is true though.
How I've done it... I've got a single ring terminal on each battery terminal, from which all the aftermarket stuff runs- horns, grips and Veypor, plus a charger/auxiliry hookup. These are then relayed, or not, as fit the role- ie the horns and grips are relayed, because IMO it'd be mad not to. The Veypor isn't because it doesn't need to be, it comes off the bike whenever it's parked anyway... And the external lead isn't because that would make it useless.
So for example, the horn's relay's simply placed where the old horn was. Quick and easy. The grips' relay is- or will be- attatched across the plate light. It's just a question of finding something that's on when you want it to be, and is accessible.