Hi Sandy,
The short answer to your question is "with great difficulty" - a search on the forums will reveal that lots of people want this functionality, but it doesn't yet exist on Virgin-Atlantic.com
Basically, any of the "flexible" options should be OK for a companion ticket, but there are a couple of ways to make sure:
1) Call VS directly, and ask them for a quote for a "companionable" fare - they can do it there and then.
2) Subscribe to something like Expertflyer.com (we have a discount deal
here) to get the accurate fare costs, based on class.
3) Take a look at the fare rules when booking a ticket on travelocity/expedia etc. The first letter of the "fare basis" is the class.
Companionable fares are classes: L/B/Y/S/W/J (in ascending order of cost). If you want more info on fare classes, a
click here might help
(PS - Are you really from the Stansted in Uzbekistan?! [:p])