I have reverse bled a few clutch slave cylinders in the past using an lever oil can.
Use a piece clear flexi-hose from the can filled will brake fluid, and place it on the slack bleed nipple.
Then pump the brake fluid out the can into the slave cylinder, thus pushing any air inline back up to the reservoir.
Make sure to leave a bit of space in the reservoir to take the brake fluid.
I found that I would pump the oil can, then nip the bleed nipple, then try the pedal a few times, then repeat until you get clutch action.
Pathfinder Tekna, 90 Defender 200tdi( in much less bits now)
Isuzu Dmax work truck