At festivals and free parties in the UK, at the peak of the scene, ipretty much everyone mixed MDMA and bootleg amphetamine sulphate, not far from Adderall. I've used combinations of the two for days on end with no ill effects. If you're just going to roll once, I'd save it for NYE, and use small doses of adderall and booze for the first two days. If you do mix X and amphetamines, you want to be all the way up on your roll before taking speed: I found amphetamines would sometimes, if tajen first, block MDMA for 12 hours or so...then half a pill would kickstart the whole MDMA dose into action. Don't drink on the day you're going to roll, to maximise effects, and maybe try and find a few 'shrooms for one of the other nights. Take a few Adderall with you for coping with exhaustion - a hit when you've come down from the MDMA on the last night might prove very handy - but try and get some sleep the night before rolling.
Spped & booze: good mix. Booze & ecstasy: can completely kill the roll. Ecstasy and speed: ideal to dance all night, but come up on the X first, and wait till you've started coming down a little to hit the Adderall. Probably not a bad idea to have a few valium and some weed at hand for emergencies, and go easy on the speed - but it sounds like it would be a little boring hanging around just drinking at a festival for two days, waiting to roll. Depending on the festival, you might also find some interesting party favours on sale - just be careful of anything that comes on a blotter these days.
It seems Americans are far more cautious about X han Brits - when the pill would good, we'd chomp 3-4 a night with sulphate chasers: when the pills got weaker, we'd chomp 10-15 (they dropped in price by 90% over a 20 year period, reflecting ever-lower quaity) and kill a gram of coke each. Starting the night on X was the norm, refueling with speed and/or more pills a few hours later, with occasional acid or 2-CB in the mix. If you;re just going to do one night on Molly, then it should be fine to do a little speed and booze on the days before. Just don't overdo the speed, or you may well drink too uch without noticing it...until the speed wears off and it catches up with you. If drinking on speed, make sure to keep plenty of esater in you, force yourself to eat at least a little every day, and ideally, take as much weed and valium in with you as you can - if you don;t need it yourself, there'll always be some acid casualty in desperate need.
And while molly does give diminishing returns, I've used on consecutive many nights and enjoyed it - just frtonlaod with 5-HTP for a week beforehand, stop 36 hours or so before you roll, and go back on 5-HTP after the festival.
By British standards, you;re talking about enough drugs for a club night, nt a three0-ay festival. But then, we;re more careful about acid here than used to be the case in Deadhead circles, and hardly ever get oxy or hydro, so I guess it balances out.