Captioning of equations is typically accomplished with a different style than
captioning figures or tables.  The equation number is presented to the side of
the equation itself.  

I am able to "fake it" by telling OOo to caption the equation, then I cut and
paste to move just the "counter field" to the correct location.  When done, I
delete the frame and everything generated as a result of clicking on "caption".
 There's a danger in this due to the fact that copy/paste could produce two
identical equation labels which confuse the cross-referencer.

Perhaps the simplest means of addressing this issue is to allow the user to
select whether they want to create a new frame around the captioned item.  The
only thing which makes this painful is that you cannot get an equation label (or
any other caption label) without enclosing the captioned object in the frame.