(2.5) installation fails with the default Installer program on MorphOS. I took a look at its installer script and tried to fix it. I don't have any prior experience with installer scripts, but I think I got it right :)
The problems I found:
1) MorphOS Installer doesn't seem to handle If clauses between "askchoice" and "choices", apparently some other installer programs can do that, but I don't know if it's correct according the specs or not (Geit?). I separated such an occurrence to two different "askchoices".
2) The IBrowse installer script assumes MUI classes being in the MUI:Libs/MUI directory, but this isn't the case with MorphOS, they reside in the SYS:Classes/MUI directory. I changed the hardcoded paths to a variable and set that if the detected system is MorphOS or not. Newstring.mcc was handled separately, and changed that too. But think twice before letting it to install the MUI classes, because it installs 68k versions and you might want to use MorphOS native versions!
3) PNG images in the IBrowse GUI appear with a pink background for some reason. 32 color IFF images seem to work better, so I changed it to default to 32 color ones instead of 256 color PNG images.
Here's the updated installer script: Install-IBrowse
And here's a diff output: diff.txt
Hope it works, and please report if it doesn't :)(The author accepts no liability for any damage caused to your system, other connected peripherals, or data files in any way by using this unofficially modified script.)
You could try InstallerLG from Aminet (http://aminet.net/package/util/sys/InstallerLG.ppc-morphos). It should support everything that the original Installer can do. It's alpha software though, it's not complete yet, but it's solid.