I have two duke cages, how can I make em work for groundhogs. I only need these for a job or two then I can get some comstocks

Bait trap them. Put the trap where the woodchucks will be.

Positive set at the burrow or crawl under at deck, shed, etc. 99% no bait needed. With only two cages, other blocking may be needed. I only use single door cages, I like to know which way the animal came from, not that it really matters. But, if doing exclusion too, it's nice to know they are all out before sealing.

I will catch all the ghogs I want with a well baited / lured cage set near a den or feeding area. A dab of good ghog gland lure will seal the deal all the time.

Like trapping any other animal. Give them what they want and like and they are caught.