There's more to it than the appraised value. It's the appraised value minus what you may owe on it now. If you own the property free and clear and and it's valued at 650K you should be able to get a 200K first mortgage easily. If that's the case, talk to the IRS. If they see you are trying to satisfy the debt they may be willing to hold off until you can get the loan processed.
If the appraised value minus what you owe is less than the debt, it may be more difficult. Most important, talk to the IRS and make sure they know what's going on. They don't want the house, they want the money.