This thread is for the Droid X and I'm not sure how to do Droid X2 boot logos. I did find this thread though. You might try asking there.
Edit: In case you are wondering why I linked to an Atrix thread, I found that while doing some research on Droid X2 bootlogos. Apparently the Atrix and X2 have the same bootlogo specifications. You will probably want to double check my findings.