I just did this today. You can use the new Labview (FRC 2015 Season) and new 2015 Driver Station with the 4-slot cRIO but you have to reformat/re-image your cRIO first. Use the cRIO imaging tool in the Utilities tab on the LabVIEW start menu. Make sure to change the computer IP address to 10.xx.yy.6 (where xx yy are first 2 and last 2 digits of your robotics team number), change the subnet mask to 255.255.255.0, and disable the windows firewall.
You will need to re-deploy the code to the cRIO after you re-image it.
I also reconfigured my older wireless bridge using the 2015 configuration utility, but I'm not sure if that was necessary.
Bridge Configuration Instructions.