Never done it, but it sounds like it would be good. One of my favorite bars does infused rums and one of them is actually honey-lychee, dee-lish, a semi-sweet lychee melomel would probably be just as wonderful, with the added advantage of being able to consume more of it before getting too buzzed to enjoy it.
I would probably peel the fruit and remove the seeds, then dice them and freeze and thaw before adding. I don't know what sort of volume you would want though, likely a sizeable amount.
Good luck! Keep us posted!