Chris; yes, you could define the slice as non-image before exporting, though I always just export and define the CSS style for that div afterwards. I may for example end up creating a background image for a particular slice, and the source file for that background image could be a separate PSD or Fireworks file.
Darroch; thanks for the Adobe link. I’m not giving up on FW ... I just don’t use it for certain things right now. It’s great for creating web graphics, but less so for full layouts. I also like the Adobe styles and image control better, though ImageReady’s far from perfect in its handling of smart objects. The Adobe Fireworks technique does require too much work IMO, esp. for a mockup.
George; I too look forward to a better Fireworks this spring. It would be a welcome change. I’ve tended to use ImageReady for the overall layout and Fireworks for occasional graphics. I’ve also been frustrated by IR’s limitations, esp. having to jump back to PS to make certain changes.