thanks for reporting, investigating. The first error (tui rpm postinstall script) is caused by libvirtd being down, but that's not a normal situation.
Conversion script was designed for Centos6.0/1, 6.2 has some (nasty
) changes, haven't managed yet to polish it. As a temporary workaround, you can start with an older 6.1 and then rebase to 6.2 with yum.