Yes, merging the 4.1.1 snapshot codebase with Scaleform April integration code should be straightforward and works almost out-of-the-box.
The problems you have mentioned are possibly a merge error (i.e. some of the Build.cs were messed up).
Try following steps:
- Get a clean UE4-4.1.1 codebase with Optional.zip extracted too (otherwise you won’t be able to build Debug Editor configuration). Be sure to remove all Intermediate folders, as this cause issues when generating projects.
- Follow all steps from Scaleform integration guide, including removal of XboxOne and PS4 folders and applying a hotfix. You can safely overwrite files.
- In Scaleform.Build.cs change the toolchain used from MSVS12 to MSVS13, and same in the windows configuration file. I believe it would work with MSVS12 too, however I did not test it.
Then you should be able to build all configurations with exception to Shipping one.