I am assuming you will be using the Lee Hood, with 2 filter slots? I know of no other way to mount a 105mm CL-PL. The hood will take a adapter ring on the front side that allows you to screw in a 105mm filter.
I have both the 18mm and the Lee Hood with 1 slot and the 105mm adapter ring.
With the 1 slot setup, with the 105mm CL-PL screwed in, you get a very small amount of vignetting, not enough to matter in most shooting situations. However if you add a 2nd filter slot, you may see enough vignetting that it will impact your shot. My hood has the 2mm filter slot.
I am mounting the setup with a Lee wide angle 82mm ring.
Paul