First you need to install:
http://www.vmware.com/download/download.do?downloadGroup=VI-RCLI-U2

This is a vmware Remote CLI tools. Install it on a windows machine.
After you install remember to log out and the log in, else you will get some error about libxml.dll cannot be found.

Then download Dell Openmanage  to the same machine that you install Vmware Remote CLI:

http://support.dell.com/support/downloads/format.aspx?c=us&cs=04&l=en&s=bsd&deviceid=2331&libid=36&releaseid=R251021&vercnt=3&formatcnt=0&SystemID=PWE_R710&servicetag=&os=LIN4&osl=en&catid=-1&dateid=-1&typeid=-1&formatid=-1&impid=-1&checkFormat=true

Put the Vmware ESX into maintaince mode.

Put tar.gz file  onto the ESX Host, and the untar the file, and then install the Dell Openmanage

tar zxfv OM_6.2.0_ManNode_A00.tar.gz
cd openmanage
sh setup.sh

Make sure that the Dell openmanage is install on the ESX.

Check if the Dell openmanage is started

/opt/dell/srvadmin/dataeng/bin/dataeng status if not then start it: /opt/dell/srvadmin/dataeng/bin/dataeng start (This commands should be run at the ESX host)

Enable SNMP in the firewall:

esxcfg-firewall -e snmpd
esxcfg-firewall –openPort 1311,tcp,in,OpenManageRequest

On the windows machine where you have install Remote CLI goto folder: C:\Programmer\VMware\VMware VI Remote CLI\bin

vicfg-snmp.pl –server <ESX Host> –username root -c appmanager -p 5567 -t 10.105.2.129/appmanager

vicfg-snmp.pl –server <ESX Host> –username root -E

If you need to test the SNMP traps you can run this command

vicfg-snmp.pl –server <ESX Host> –username root -T