I finally had a chance to tag one of Idaho's famous big mule deer; how do I have it measured for the record book?

You can do a "green" measurement to satisfy your understandable curiosity but the official measuring process cannot take place until the rack has dried for 60 days. All antlers will shrink slightly as they dry. Dry them in the air at room temperature; trying to reduce shrinking by freezing the rack is not allowed. Then call Fish and Game at 208-334-3746 for a form to arrange for one of the people who measure for Boone and Crockett or Pope and Young (for archery trophies) to meet with you and your trophy.