If you don't list it, most any drug can get you into just as much trouble. For any substitution be prepared to give 60cc. Also be sure it falls within the 91-97 degree temperature range. Most often the test containers have a tape on the side indicating the samples temp. Whatever the container, it must open quietly.
Toilet paper is a convienient, provided, insulator.
By using a vial or condom taped to the inner thigh, you can get around the gown as well as the temperature requirement. Practice until you have made it a fine art. A man with his back to an observer can do just as well. Abbie Hoffman suggested a few drops of urine on the seat or on ones shoe as an added measure of authenticity. If you can't pass the test - screw over the chain of custody.