Modifying Self-IP's without deleting the configuration

I'm upgrading 2 x 3400's to 2 x 3600's and want to run all the configuration in parallel for testing and the implementation of ASM.

 

 

Following testing, I need to change the Self-IP's to the IP's of the existing boxes (once I've removed these) so I can avoid changing all of my servers and DNS.

 

 

Is there an easy way to do this, or am I trying to be too ambitious?

 

 

Cheers.