Word 2007 has a "Find all word forms" option in the Find and Replace dialog.
This, among other things, will let it search for all verb forms (among other
things). That might be what the person was talking about. For example, with
this option enabled, if I search for "have", it will also match "having". If
I search for "is", it will also match are, be, was, and were (for example).
But, there's nothing in vanilla word that would "accept" only present tense.
There might be an add-in that does that, although, I've never heard of such
a thing.