Well, if the uninstall-string (you can see that in the 'Show/Edit info' is something like 'MsiExec.exe /I{blablabla}' you can try changing the '/I' to '/X'... Other than that, there's not really much to do...
...With ZSoft Uninstaller, anyway, (yet)
Version 2.5 (the upcoming version) will probably be able to help you (once I get done with the feature).