Depends on the format of the Oracle VM Template, if it's in VMware's .vmdk format or perhaps and .ova/.ovf or other supported images, you can use VMware Converter to import onto ESXi. VMware Converter is free and is very simple application to use that can run from either Windows or Linux desktop.
Take a look here for more info and download: http://www.vmware.com/products/converter/
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William Lam
VMware vExpert 2009
VMware ESX/ESXi scripts and resources at:
VMware Code Central - Scripts/Sample code for Developers and Administrators
VMware Developer Comuunity
Twitter: @lamw

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