I've never used a clamp in conjunction with squeezes, though I was doing a ULI/Erect Squeeze hybrid for a while. I would basically use one hand as a manual clamp with ok grip at the base, fully erect. Then pulse 1-2 second squeezes around the shaft with the other hand. I would do about 25 squeezes per hand, then edge a bit, then do another round.
I am currently doing clamped edging with a Cable Cuff Pro brand clamp I got at Home Depot. I'm building up to more time clamped, but usually I do rounds of 5-10 mins clamped edging, then remove clamp and massage/edge for 5 minutes, then clamp again.