If you can remotely shell into the Mac (ssh), then you should be able to build and sign your project from the command line. It may require some setup beforehand, but xcodebuild
and xcrun
should get you where you need to go. (This is the same kind of thing folks do to get automated continuous integration builds set up.)
Doesn't get you out of using Xcode or a Mac, but maybe gets you out of having to be physically sitting in front of that Mac to get work done.
Further reading: