If you're going for the Higher Than Most achievement as well, then check out my solution for that. If you're getting closer and closer to getting that one, then you'll get this along the way.
(I copy and pasted these tips from that solution)
1) Try to keep a good, long streak going before the alternate-strumming part. If you have around 400,000 by the tim the alt-strumming starts, you're in very good shape.
2) Use Star Power as often as possible, try to use it as soon as you get it. Having full SP for the alt-strumming part will get you a lot of points. If the lead guitarist thinks they'll have trouble with the triplets solo, then save SP for it. No point in failing with a minute and a half left.
3) Watch your score throughout the song. If you can't keep a good streak going during the end solo, then try to have a score of somewhere around 550,000 once the alt-strumming part ends.
**NOTE** This is very important to know, me and Aero found this out the hard way. If you're playing online, only the HOST will get the achievement. So if both players are trying to get this, they'll have to have 1 person host and get it, and then switch hosts and do it again.