Wow, I would be a zombie if I took 30mg of vicodin a day!
Normally if someone is on Methadone that they have a rx for, they usually get drug tested fairly often and aren't usually allowed to take other narcotic pain meds. To my knowledge the purpose of methadone is to help those that have had drug addictions. It takes the place of the drug they used to take.
OP you should be fine taking the Vicodin with the test, just don't overdo it