Forget it, this is typical IBM second-rate rubbish. Firstly, the fix above doesn't work on Release 1, so you have to edit the bin file with vi to change the 'tmp' directory. When you've done that, the install proceeds normally.... until it goes to install. My /opt size is 2Gb with over 1Gb free, the installer says it needs 523Mb of free space, but then goes on to report that it needs 1Gb... then bombs..... Better to stick with OpenOffice.
Edit: OK. I finally installed it in /usr/local/ibm
It's obviously a tad faster than the betas but on my ancient hardware is no speed demon... If you like mucking about with vi, give it a shot
I'll probably uninstall it, then remove something from /opt (Google Earth) and try and install it there, then reinstall Google Earth...