Here's something I posted over at fritter about transferring segments from a PC to a mac.
One of the ways to do segmenting is to make sure the mac file is in hqx format.
If it isn't in hqx format ...
Using hfv explorer create a temp hfv volume using
"format new volume" from the menu.
You can delete the temp volume later.
Make sure the temp volume is big enough to hold the mac file.
Transfer the mac file from the PC hard disk to the temp volume and then transfer it back to the PC hard disk but this time don't let the automatic file transfer happen but choose the binhex transfer option.
So after that you will have a macfile.hqx file sitting on your hard disk.
Now you can use a PC text editor to split the hqx file into floppy sized chunks naming them chunk1 chunk2 etc.
Copy the chunks onto a PC floppy and transfer them all to the mac.
On the mac side you can then use a text editor to join the chunks up (in numerical order) and then use stuffit expander to unstuff the joined hqx file.
I think Simpletext won't handle large files so use the free BBEdit Lite text editor.
You might have to give BBEdit Lite more memory than it's default for large hqx files.