You can't select Playlist/Album/Artist/Song by letter, we experimented with it but it's unusable due to the constraints and speed of the KCA-420i, there was one version of the firmware with it in but it's pretty unlikely that you have this installed on your Intravee.
You probably have firmware V5.31-306 installed, maybe 5.40-323. If you register your Intravee serial number (see the FAQ at
http://www.intravention.co.uk/forum/index.php?topic=1110.0 ) then you can update to V6 firmware and we can tell you which firmware is installed on the Intravee.
If the Intravee is set for 'Advanced Search' then the search menu will be a scrolling list of items, with V5 firmware you must enable Enhanced features to enable Advanced Search.