Edit
(re: comments, I've misread the "I currently have a VF Page...")
Help for custom objects won't let you put a static resource there but you could try to make-do with "action" parameter?
<apex:page readonly="true" action="{!$Resource.resource_name}">
</apex:page>
This should redirect immediately.
Original
http://www.salesforce.com/us/developer/docs/pages/Content/pages_compref_sectionHeader.htm
help
The URL for the page's help file. When this value is specified, a Help
for this Page link automatically appears on the right side of the
colored title bar. The URL must be a fully-qualified, absolute, or
relative URL; JavaScript URLs aren't permitted. Invalid URLs display a
warning icon instead of the help link.
So if any link can be used in the "help" attribute and it can even point to external website (absolute URL):
<apex:sectionHeader title="..." subtitle="..." help="{!$Resource.resource_name}"/>