Didn't they make it so you can enter a pre-cata raid zone without a group?
You can - using a trial account:
1. Invite your trial account toon (can be level 1) to your group.
2. Run the following command with your trial toon: /run SetAllowLowLevelRaid(true).
3. Open raid with your main character.
4. Have fun.
Your trial account can also be on the same Battle.net account.
It has to be level 10 now m8.