Well, just spent a couple of hours in this. Was able to jailbreak successfully my DXi!
Except I could not get KUAL to work. Error: Title not signed by registered developer.
Tried different KUAL versions, different dates,
updating the keystore via the binary and manually (usbNetwork/ssh), reinstalling MKK, rebooting, and a combination of everything. To no avail
I'm able to launch Koreader via SSH, though, so no biggie I guess.