HP SIM will work with ESXi 5, so long as you have the HP ESXi Offline Bundles installed (which will include the HP ESXi CIM Providers and HP SIM agents)
You can download an ISO of HP ESXi 5 will all the offline bundles pre-installed here (registration required)
https://h20392.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=HPVM09