Define "loppers".
Something like this?
If you can take it apart, that would make sharpening easier. I wouldn't use the wicked-edge clamp but you might be able to use the hones free-hand if you have any coarse enough. The sharpmaker hones might also work free-hand if you have a coarse enough hone. In either case, i would work free-hand, holding the blade still and running the hone across the bevel. The key is to be able to remove sufficient material from the bevel to apex the edge, and that will likely require a
very coarse hone. These are chisel-ground, so you should only sharpen the beveled side with maybe a single swipe to remove the burr from the flat side. Simply paint the edge-bevel with marker (red Sharpie works very well) and then run the hone along the bevel at the proper angle to remove all of the marker = matched bevel angle. Grind the bevel at that angle until you achieve a clean apex.
The dremel is a crude sharpening instrument, can do a heck of a lot of damage to an edge in a hurry, you are better off using a 1x30 belt-sander or just a $4 hone from the hardware store. That's my $0.02. FWIW I sharpen my outdoor tools (loppers, trimmers, axes/picks, scythes, mower) on a HF 1x30 with good results using 80 & 120 grit belts followed by some finer grits from Lee Valley if I feel the urge.