OK, I know there are some people who don't believe GD is a real disease... but as somebody whose had insulin-dependent GD for three pregnancies, it is...and it has real consequences if not managed (especially if your numbers are high enough to require insulin/glyburide/etc.)
I don't think your goal should be to "pass" the test, but to determine whether or not you really have it--because if you do (insulin-dependent GD), you're facing very real increased risk of stillbirth and early placental deterioration. (I'm not so concerned about macrosomia...as I honestly think that's over managed with c-sections too much of the time.)
It's great to want a home birth. And there are midwives who will attend you if you have diet-controlled GD, but probably not insulin-controlled. Still, the real goal should be a healthy baby and healthy mama--not giving birth at home, if that at all compromises those things.
Having said all that, eat a high protein, high fat breakfast before the test. Eat normally the night before... neither too low carb, nor too high. Choose low-glycemic load carbs if you can. Drink plenty of water. Walk during the test if you can.
Mom to DS(8), DS(6), DD(4), and DS(1). "Kids do as well as they can."