I believe the track packs have codes that can be used to download the songs. However, I think the export codes are only good for transferring disc songs to the hard drive. I can't say for sure since I don't have Lego Rock Band or a PS3, but that's how it worked for past products.
[quote name='bigdaddybruce44']Pretty sure you need the disc to export the songs. Couldn't find anything on the page for the promotion, but I found this on GameSpot.
Here's what you have to do:
1. Go to Rockband.com/Lego-Export
2. Enter the code from the manual
3. Enter the 12/13 character code into the PSN store
4, Click download on the Pack.
I've already done steps 1 & 2 so whoever wins will have to do steps 3 & 4.
Okay, my apologies. I've done a bit of research and I was wrong and a few other people were right (sorry guys). You will need the Lego Rock Band disc to export the songs.
But if anybody bought a used copy or intends to do so, this contest would be perfect for you.