first, scan your system to be sure file: VMadditions.iso is available and its location.
2nd, start your virtualized os/2 system.
3rd, click "cd" under title bar. then select "capture iso image"
a dialog default dialog box location opens. it should show the additions iso. if not, use the box control to find the file in the location your scan found it.
4th, double click on file name box will close. check mounting by clicking "cd" under title bar. previously greyed "release cd" will allow the release of the iso.
5th, from os/2 desktop, then system, then drives, find and open cdrom drive object. in the os2 folder is "os2inst.exe". double click and follow directions. this will give you higher resolutions, folder integration, etc.
good luck!