From looking at the data plate for a MEP-017A online it seems these have the same reconnection options as the MEP-016 series shows in their tech manuals (maybe different than the 016B/D/E based on some peoples real world testing). These are 120V 1 phase, 240V 1 phase, 120V 3 phase, and 120/208 3 phase. As I see it there are a handful of options for home backup here:
1, if you only need 120V (there are not that many 240V houshold appliances you can run on 5KW, well at least not while running anything else at the same time), in this case simply set it to 120V 1 phase and connect your transfer switch the same as you would any 120V only backup generator. One advantage of running in 120V only mode is you don't have to worry about load balancing, you have the full 5KW available everywhere. If you were to modify it to run 120/240 split phase you would have 5KW availble total, but only 2.5 KW per leg on the 2 120V legs. Trying to pull 5KW out of one side of those legs would likely burn out the generator. I suspect this is why the military did not put a 120/240 split option on the switch, makes it more idiot proof.
2, If you have to have 120/240 split phase and don't want to modify the generator, you can opt for a 120/240V transformer with split phase taps, these types of transformers are often used for offices, etc. in industrial locations with 240/480 3 phase power to supply 120/240V for lights and office equipment. The advantage of this method is you can still use the full 5 KW without load balancing, the downside is these transformers will likely cost you a couple of hundred dollars used, and are heavy.
3, Remove or modify the reconnection switch to bring out the neutral in 120/240 split phase mode, any commercial (not residential) generator tech should be able to do this in about 30 minutes (at least for the remove option). The danger here is if you leave the switch in place it will likely not function right unless you add a second switch/remove the neutral connection, then there is still the danger of someone changing one and not both switches.
Ike