Hey, I'm afraid that an update of dactyl in Jessie is unrealistic. Finding and backporting the compatibility-relevant changes is non-trivial to say the least. The diffs I had to import from the upstream repository to make it even start up amount to around 3000 changed lines, and even then most functionality does not work.
It looks to me like a removal from stable is once again the most reasonable thing to do (this already happened once in wheezy), which I am going to call for if there are no objections within the next few days. (With the way Iceweasel security updates are dealt with these days, I'm beginning to doubt that a complex add-on like Pentadactyl is even worth maintaining in Debian at all.) Cheers, Michael