Hopefully you'll find a better way, but if you don't, and if it's a monochrome vector image you need, you may need to use the same cumbersome technique needed to use custom images as bullet points:
IndyFont Demo: make your own (1 character) font
(Better step-by-step instructions from Lynda)
(Better writeup on Typophile)
Basically it's a quick and easy way to create one-character document fonts within InDesign, to use as textual icons etc. Quick summary:
- Get the free One-Character Demo of Indesign-based font maker IndyFont
- Install it as any indesign script.
- In the Indyfont bit of the Script panel, 'Create font template'
- Paste in
[Black]
vector artwork. The red line is the base line, adjust the green line to make space.
- Save...
- If you're in Indesign CS5 or above, you can include it as a document font (in a folder called 'Document Fonts' next to your
.indd
) without having to install it system-wide.