MineOS gives you a web interface that lets you set up profiles.
In there, you give it the url of the .zip that contains the pack. It downloads that .zip, stores it locally, then extracts the contents each time you ask it to make a new server with that profile.
I haven't made any changes to the 1.7.10 files, so the FML errors are either a problem on my end or are tied to the contents of the FTB server .zip file.
If it's me, then there is some flaw in my distro that just doesn't like 1.7.10 for some reason. Java versioning, I'd guess. Lots of painful debugging.
If not, then the FML inside that zip is incomplete or is unpacking itself wrong.
Typing this, I understand that I'll probably have to go through the FTB support instead. Sorry to bug you guys. But do put a not here if you hear of a way to manually fix this. The FTB team seems a little slower and more scattered. But I don't blame them. They have a LOT on their plate.
Cheers.