To be very honest, I don't cook in a microwave either at home or at work so my answer might not be appropriate to the domestic scene
I know some people swear by the microwave as an indispensable tool - I use mine to soften butter for my toast at home LOL
My mother used to do a roast chicken in a convection microwave with the grill but cannot remember if she ever did the potatoes in it.
I suppose you could put the peeled potatoes in a bowl, a little water, salt and bay leaves, wrap in clingfilm and cook them through until just cooked.
Remove the clingfilm, discard the water residue, remove the potatoes and toss them in a little seasoned flour, melt some butter and return the floured potatoes to the microwave in a deeper container, along with the butter.
Cook on high or with the grill on and stir occasionally.
Hopefully this should give the required look and result, though technically not a traditional roasted potato as we know it.
As I've mentioned, this is my imagination and have not tried this method, but it should work nonetheless.
I'll defer to the microwave pro's who'll be able to provide a better recipe.