I haven't messed with custom characters in a while, but the limb names should be irrelevant. As long as your character is in the .x format, you only need to reference the correct animation frames in the .fpe (and, if necessary, in any lua script.) These may and probably will vary from the stock characters, of course.
MAME Cab PC: i7 4770@3.4Ghz (passmark 9945), 12GB RAM, Win 8.1/64, GeForce GTX645 (passmark 1898); Shiny new laptop: i7 4800MQ@2.7Ghz (passmark 8586), 16GB RAM, Win 8.1/64, GeForce GTX870M (passmark 3598); Old laptop: i5@2.3Ghz, 8GB RAM, Win 7/64, Intel 3000 graphics