1> create HP CMS (Center Management Server) and install HP SIM (System Inside Manager) 5.2 on it.
2> install HP Insight Management Agent 8.0 on ESX host http://virtrix.blogspot.com/2006/09/hp-insight-manager-agents-for-vmware.html

HP SIM did detecte both ESX hosts. However, it shows "degraded or failed" under "Health Status" column in SIM even though there are not.

log on ESX, run "server hpadm configure" did the trick.

This is my working /etc/snmpd/snmpd.conf:

rwcommunity mycomstring 127.0.0.1
rocommunity mycomstring 127.0.0.1
rwcommunity mycomstring hpcms.mydomain.mag
rocommunity mycomstring hpcms.mydomain.mag
trapcommunity mycomstring
trapsink 192.168.14.19 mycomstring {I bet "trapsink hpcms.mydomain.mag public" will work too.}