Install aggregate with larger virtual machine

I have a number of instances of ODK aggregate on Google app engine.

I need to add one more.

The lst time I did an installation, I read in the documentation that because I had more than 7000 submissions I would need a custom deployment with a larger virtual machine


I managed to find some documentation to do this last time but can't track it down now. Can anyone direct me? I remember it being about changing just a couple of lines of code in the default installation.

Thanks for any help!