Two things I can think of:
Use TiVo's feature request form
and suggest they need to change wishlist searches so that it chooses to record from the highest channel number first, instead of from the lowest channel first like it does now.
Suggest to your cable company that they need to put the HD channels lower than the SD channels in the channel line-up.
Neither of which I think will do any good, although your chances are ever so slightly better contacting TiVo.
*(You wouldn't want both to happen because that would just reverse your situation.)