Go to Download on the
www.gowerpoint.com website and you will see full instructions for installing uBook. You need the ARM version for PPC2002/WM2003.
It does unzip to a *.cab file. You should not try to unzip this, but should copy it to anywhere on your Axim (they suggest My Documents but it does not matter) and then open the *.cab file with a file explorer. The uBook.exe program will self install and the *.cab will delete itself.
Incidentally this is a very nice free e-book reader whichis a good complement to MS Reader.