Thanks JRL. The only difference I encountered with those instructions is as follows:

1. Wen I de-compress the Network Access archive using StuffIt Expander (per your original instructions), one of the files that appears is called "Network Access.image".

2. When I open the Floppy Image Writer, the only files it allows me to write are with ".img" and ".imz" extensions.

3. I change the "Network Access" extension from ".image" to ".img".

4. I then select "Browse" under "Write Floppy," locate the image file and click "Open," click "Start," and in less than a minute the program makes a sound indicating success.

After following this process, however, the floppy disk I created will not boot in either my Mac SE/30 or my Classic.

Thanks again for your input!