| Boost,
Have you tried warming the food slightly?
Also, it sounds basic, but have you tried leaving it in his viv overnight(away from heat source)?
Then theres the bloody nose technique, cut the nose of the rodent.
Also, if you have live rodents in a cage, then try getting a thawed and placing it in the live rodents cage(without them in in) and roll it around a bit, then dust off and try to feed, sometimes it gives a stronger smell, and some snakes go for that.
let me know if you have tried these, if not give them a go.
Neil | 
