Modifying usergroup mark-up based off custom field
 

I have asked over at vBorg about this with no luck, I was hoping someone over here could unofficially shed some light on this (or reply on my vBorg thread located here).

Basically, I have multiple VIP usergroups that have the same permissions and I want to merge these users into one usergroup and create a custom field in their profile to allow them to select their VIP colour.

To modify their markup username, I will need to use the fetch_musername hook, but before I can do that I need to get the results of the custom profile field (a drop-down list of colours) and then send this variable to the hook. This is the bit that's confusing me.

If anyone can shed some light on how to accomplish this, I would appreciate it!