According the the website, you have to go to an interim 5.0 release first (5.0.0 relase 1644) first, then jump to OS 6 if you are doing it over the air. If you tether to the computer first, you can go right to the version 6 software.
http://support.vzw.com/pdf/system_up...rate_email.pdf
http://support.vzw.com/pdf/system_up...onal_email.pdf