Same problem for me but at least I did it !
I was in 6.1 and now 9.2 !
I used rxTools 2.5.2 and launcher rxTools.dat with
http://www.reboot.ms/3ds/
Then injected FBI on HealthApp on SysNand
Then Go to fbi and installed Sysupdater.cia
Then go back to home menu, Sysupdated created a shortcut on the menu, launch it
And now click upgrade and wait for CIA installation.
PS : You must download 9.2.0-20E(full).zip before ! (if you get an EU console)
https://mega.nz/#F!IApGwLJL!kYHL5jMlDfd0rmn6a8DaFw