Lotus completed the notes 4.6.x OS/2 client, but chose not to officially release it (for whatever reasons).
But it *is* hidden within the 4.6 server install. Here's how to install it.
Copy the contents of the SERVER\OS2\INSTALL directory (and subdirectories) from the CD-ROM to a temporary directory on your hard drive (so you can edit and save some text files)
In the temporary install directory:
Edit the P32WRK.PKG file and change the line DISPLAY='NO' to DISPLAY='YES'
Edit the NOTES.INI file and add the line UNSUPPORTEDCLIENT=1
Run INSTPM.EXE Go through the custom server install. You will now see WORKSTATION listed in the modules you can install.
Once installation is completed and you've rebooted, go into the NOTES.INI in the \NOTES\DATA directory and change the line KitType=2 to KitType=1. Rename the "Domino Server Administration" icon to "Lotus
Click on the icon and set up the client just like the Win32 versions. From what I've tested, all the functions of the Notes Designer 4.6.1 are there.
The only thing I haven't gotten to work correctly (in the 20 minutes that I looked at it) is sending internet mail to the SMTP gateway (it pulls mail from the POP server just fine).