pathfinder build help: nonlethal gun rogue

[Aemoh87]

I want to build a nonlethal rogue that uses guns. SO far I have 4 levels rogue (scout, thug), 1 level gunslinger (???), then the rest sleepless detective because its interesting. I was thinking enforcer, bludgeoner, sap master with a good mix of melee and ranged nonlethal sneak attacks. Also I want this build to be focused on dex and int.

How do I make ranged nonlethal sneak attacks good with guns?

[Sayt]

The first thing that comes to mind is the Merciful magical weapon quality.