Firstly, OpenQRM is more supported on Debian than CentOS. Not that it is a bad thing, just that majority of WHT's members are comfortable with RH. I personally found it very hard to set it up on the latest CentOS -- may be I went wrong.
Secondly, you can't run OpenQRM on VPSes - makes no sense at all. OpenQRM is supposed to be installed on a dedicated server. It basically creates VPSes in a high availability cluster sort of thing -- the point of calling it cloud computing!
Load balances the VPSes on different nodes. Moves VPS from one failed node to a backup node. Basically, trying to keep your services up!
Check out a commercial and simplified software called AppLogic
. A friend of mine uses and says that it is fantastic.