i don't think i've ever seen a first person cover system
Breach
Not out yet, but comming to XBLA soon
Uses 3rd person view when you take cover, then when you peak out to shoot, back to 1st person.
Only way to make it work.
Otherwise, in FPS only view, you really are limited to peak and lean for cover... and lots of games don't even have that.... it's crouch toggling or strafing in and out of cover.