FWIW, the latest version of the A380 in the development repository, now calculates the Vref and Vls speeds for you on approach.
On the MCDU, click on the APPR tab after you have descended to at least 10 000ft you can select either flap 3 or flap full configuration.
Note that the calculation is only updated when you change to that page.
The development repository at https://gitorious.org/airbus-aircraft/a380
will sometimes contain an aircraft that doesn't work properly, at the moment I'm trying to get it into a stable release to work with 2.12 release, but there are a few small bugs..