Here's some documentation on getting started, using the Sense Linker and Live Rule Tester tools and a tutorial on writing transfer rules. This documentation is also in the FLExTrans Documentation folder in the install folder.
Refer to Ron's thesis, A Linguist-Friendly Machine Translation System for Low-Resource Languages for a detailed description of the system.
Ron welcomes your emails for any help you need. Write to flextrans "dot" help "at" gmail "dot" com.