Externally: I would try different foot baths (may be, except those with baking soda) to see what is immediately effective and maybe rotate after a few days just to change the alkalizing elements. I would be careful with the temperature, the skin might be too sensitive or too insensitive, so maybe not so hot water in the beginning.
Even pure 3% h2o2 foot bath and in spray throughout the day. Diluted ACV might be also good for spray. Alternate.
Internally: I guess so much that could be done. Maybe ACV could help loose some body water? BSM could be good for its nutrition. It is not that I would not encourage the ML drink, but one has to begin somewhere. I am a proponent of small steps. KISS principles. Big steps might be harder at first, they can be done later.
I would suggest the foot baths and if effective will help the person to eventually walk and hence do exercise. The foot baths are also un expensive and easy to make. If effective, will also prove that pH balance principles are effective and more from such principles could be achieved.
Maybe cayenne pepper internally.
If I were to loose my legs I would surely consider internal (oral) use of food grade H2O2 (0.05%).
For a diet, the minimum would be to avoid any sugar, starchy food, soda pop, fast food, industrial food ... at least eat whole food. But there is so much to be done that it will be overwhelming.