I have my neighbors who have a mule. Desensitization is done in the same way as horses, but first they have to gain the confidence of the mule!
Most of the work was to desensitize it to the touch, to sit next to it, to pass behind it. I do not know if it will be the same for you ... Once this big stage of 1 month, they could start brushing, putting on the halter, strolling in hand and then saddling it ... E
ach mule to a rest of character Of the donkey, just find out how it is characterized to be able to move forward with.
Compared to riding it, they do that dressage for the moment.
I hope this helps, bye :)