Ah, yeah, that's a kinda tricky one I keep forgetting to explain/add to the archive.
Basically, to fix this:
- download the '1.7.1 alpha for source builds' package
- create a Source directory under your HammUEr directory
- create a HammUEr and HammUErRuntime under that
- copy over just the HammUEr.build.cs file from the package to the HammUEr directory, not the rest of the source files
- copy over the entire contents of the HammUErRuntime directory
Compiling and packaging your project shouldn't be a problem any more.
Let me know if you do run into any more things or have questions.