When I try to talk to Kevin by clicking on him, he usually moves away too
quickly. It often takes me a dozen or more tries to "catch" him. Is it possible
to slow him down, or add some waypoints, or something?

In general, it's much harder to talk to the friendly NPCs than it is to shoot
the unfriendly ones! But Kevin is the worst.

I agree with mhwombat? But the only way to reduce the speed is affecting globally 
all droids.
Maybe we could change waypoints to use a smaller path...

Ples, remember that he often gets RH mode...

I agree that some NPCs are too fast for their own good - but I'm not sure
slowing them down is always the right solution.
Hovering over a NPC could bring up a sort of pie menu that would stay at the
cursor position, while the NPC would continue wandering around. The pie menu
could include the ability to activate the chosen program on this NPC or start a
conversation.
Friendly NPCs could also stop moving and turn to stare at Tux when hovered over
(as if Tux called to them), though in some ways that might be worse than slowing
them down, and can get NPCs stuck under the cursor if the player is idling...

I agree with Infrared.
Kevin is also often in RH mode.

What about adding more waypoints on the way? This would make Kevin stop more
often inside the building allowing the player to catch him.

Shouldn't Kevin be stationary and staring at a computer screen?