IBM has released the IBM VIBs (vSphere Installation Bundle) for ESXi 4.1U2 (Update 2) and 5.0 so customers can now create there own custom ESXi images.
The IBM providers for 5.0 are now posted to Fix Central – here (updated link July 2012)
Otherwise you can also find them by:
Going to Support and Downloads at ibm.com
Choose Fix Central
Right side and do a search for – IBM CIM Providers for VMware vSphere Hypervisor 5.0
vSphere 4.1U2 (Appear to be no longer available – July 2012)
If you have any queries about these VIBs, the best place to post your question is IBM’s System x Server forum here