Just take the Two-Fisted Shooter feat and move on.
You can treat the hand crossbow as an off-hand weapon, and you can reload it one-handed as a free action. When you score a critical hit and have a loaded hand crossbow in your off hand, you can make a ranged basic attack with that weapon as a free action. (MP 140)
This will let you reload a hand crossbow with the hand you're holding it in, and eliminate any other silliness.
It's totally possible to juggle weapons like your talking (actually what you probably want to do is juggle the rapier and the hand crossbow in the same hand and keep your off hand free). But really, there's a feat for this, that has an additional cool mechanical benefit. Take that and move on.
One more possible solution if you don't mind spending a minor every other turn or so.
- Start turn with unloaded HCB in off hand, rapier in main.
- drop rapier (free action)
- Load HCB (Free action)
- attack with HCB (standard action)
- Reload HCB (free action)
- Pick up Rapier (minor action)
You now have a loaded HCB, and the rapier is back in hand. If you do this every other turn, you can attack with the HCB and have the rapier available for opportunity attacks or melee situations.
