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.
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
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.)
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.
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.
Please let me know if you encounter any problems or better alternatives for this howto. I plan to add screenshots later.