I would use the names of those you can either identify or get off the slipcase/case insert

Or they could be contributed without roles.  Roles aren't required.  The world won't end.

This is actually covered by the rules:

Quote:
If an actor is credited by name but does not have an associated role, you may use the film itself, or another source to identify the role. However, mass copy from a third party commercial database which violates their stated usage license is not allowed.

So, as long as you don't mass copy froma third pary commercial database, you can use another source to get them.

As scotthm says, this is quite common...especially for TV shows, which this is.  What I usually do is check a couple of sites and settle on a name that makes sense.  For my contribution notes, I usually write something like: Roles were not given for the first nine actors so I used other sources, as allowed by the rules, to determine those roles.

Quoting Stevegauss:

Quote:
I got the info from the Battlestar wiki which has proven to be very accurate over the years. I'll put the web address in the information spot if there are any problems or questions

That should be good. I've done a few espn series where no roles were given and the cast was huge (Playmakers, I'm looking at you) and TV dot com made it look much nicer by providing almost everyone a role. Official is always preferred, but TVcom is a great site for auditing TV seasons.