Yes, individual PNG-24 files from Photoshop is what you want. In Photoshop, File>Scripts>Export Layers to Files; browse to save location; choose PNG-24 as the file type; check transparency. Prior to this, if you have floating imagery in any layers in the Photoshop file, you will want to place 1-pixel dots in 2 opposing image corners on those layers, so the all layer sizes will be exported at the same size, for layer-registration when composed in Fireworks. Then delete those dots in the exported PNG files and resave.
Then you will need to compose the layers in Fireworks. Once you get your individual layers in PNG format, you might want to pose this question in the Fireworks forum.
