Here is a step-by-step guide to set up the LisaEm emulator with Lisa Office System on an emulated 10MB ProFile drive. (I thought ProFiles were only ever 5MB...) This process has been tested on an Intel iMac running OS X 10.4.9.

1. Download the emulator from here.

2. As per Zydeco's AppleFritter post:

   Get the ROMs collection from here: http://www.apple2.org.za/gswv/a2zine/System/A2_ROMsCollection.zip

   UnZip it and rename 3410175H.bin to boot.hi and 3410176H.bin to boot.lo.

   NOTE: This tripped me up initially. I first attempted to rename those files in the Finder, and it appeared to work; however, OS X retained the additional ".bin" suffix (hidden), so the filenames were actually "boot.hi.bin" and "boot.lo.bin". That caused the emulator to throw an error about the checksum, then crash. I had to rename them in the Terminal, like so:

   mv boot.hi.bin boot.hi
   mv boot.lo.bin boot.lo
   

3. Make a folder under your Mac OSX home dir, called LisaEM. Inside it, put the LisaEm app, boot.hi, and boot.lo, and the five de-serialized Lisa Office System disk images from here or elsewhere: http://www.applerepairmanuals.com/lisa/software/LOS_archives/

4. Un-binhex the LOS files with Stuffit Expander. You do not need to convert them any further.

5. Launch the LisaEM app. When it opens, go to Preferences. For "Lisa ROM", browse to boot.hi. Then hit Apply.

   NOTE: This step causes two files to be generated: a "boot.ROM" file in the same directory as the boot.hi and boot.lo files, AND a lisaem.conf file in your home directory. There does not appear to be a way to override that location; furthermore, that conf file contains entries with absolute file paths to the ROM and (later) hard disk files. So, if you move your LisaEm files or rename the enclosing folder, things will break unless you modify the conf file manually, or re-set your preferences (which may in turn kick off a whole new hard drive setup process -- I don't know yet.)

6. Then go to LisaEm's File menu and selected "Run". A dialog box pops up asking, "Hard Drive Size?" I picked the 2nd option, "10M - any OS". After a few seconds, the Lisa self-test screen appears, followed by the Lisa's "Startup From" menu.

   NOTE: This step causes another file to be created in the same directory as the ROM file(s); a disk image named "lisaem-profile.dc42." This is your emulated hard drive. You can't mount it under OS X, because it has an unreadable file system to OS X.

7. From the Lisa's "Startup From" menu, select the first option, start from floppy. The next screen shows a picture/dialog indicating that you need to insert a floppy and continue.

8. Go to LisaEm's File menu and selected "insert diskette." From the dialog box that appears, first select the "All (*.*)" option from the top "Enable" popup menu, then select the first of the Lisa Office System disk images.

9. Then hit the Lisa's Continue button, and after a couple seconds, the LOS installer should appear. From there, follow its prompts to install LOS to the emulated 10MB ProFile hard disk. Whenever it asks for another floppy, repeat the "insert floppy" process from LisaEm's File menu.

After this, the emulated Lisa will be able to boot from the ProFile hard disk. When it's booted, you can insert more diskettes to load more software such as LisaWrite.