I did a M.A dissertation on Alkan's Piano music 10 yrs ago, having listened to and inspired by Raymond Lewenthal's performance of Le Festin D'Esope and Grande Sonata (3rd movt), and based most of my thesis on these pieces.
My memory tells me that Liszt once mentioned that Alkan was a better viruoso than himself, and that some of Alkan's music was even too difficult for him to play. Alkan wasn't a popular figure in 19th Paris although he had at first a very promising concert career; in his 20's audiences responded very favourably to him. But then a series of events happened which stopped his flow of success - among them the French Revolution. The themes/culture surrounding music at this time was moving into the realms of superstition, supernatural, fantasy, fin-de siecle (frankenstein), and found his music too "old fashioned". Although his structures are very rooted in the old music of the Baroque period his extrordinary musical writing is ahead of its time.
I dont know of any other stories though on Liszt and Alkan. Chopin was Alkan's closest friend.
Rant over..!