It depends on the game, the engine and the files themselves. It's not just replacing the files from one version to the other version, and some games, while they use the same type of assets, may require you to adjust some things so they work properly (for example, a working word-wrap for the Vita version as most games don't really render text correctly just because you replace files).
There is no tutorial to do this other than to compare both versions, check their files, and mess with them to make a paych/injection of what you want, which in the worst case may involve making your own tools and so on.
Of course, depending on the game the process may be as easy as just replacing a .txt file, but those are few and I could say almost zero for Vita.