No one in IRC seems to have any ideas on this one *g*, although if you turn custom comment pages off, you should be able to use ?style=mine to help? It might be worth suggesting this on bugzilla as a useful option - or waiting a few days, because when I was trying to answer this I noticed a whole load of changes in Customise Style, just since yesterday!

Hopefully someone with more ideas will turn up...

ETA: And I see they already had! Awesome! *goes to set site-theme comment pages*