does anyone know how to remove front mcs seats from the slider mechanism while the seats are still in the car?

the upper part of the seat looks like it's attached to the slider mechanism by 4 button head allen screws, but i can't figure out how to get at those. is there a special tool or do parts of the seat skirting come off?

i'm replacing my front seats, but i want to use the existing sliders.

thanks,
flyboy 2160