I followed the instrctions that were given. I downloaded the application, and I set permissions as indicated below:

Get it here http://repository.apptapp.com/packag.../Installer.zip
Use Independence to install installer and ssh
SSH into your phone and issue the following commands:
chmod 777 /Applications
chmod 777 /Applications/Installer.app
chmod 777 /Applications/Installer.app/Installer

However, whenever I go to install something now, I get "Main Script Execution" failure. It downloads, but it will not install. I tried to reinstall Installer.app through Installer.app (uninstall->installer.app->reinstall button), but that doesn't work either. Stranger than that is the fact that it shows its size as 0 bytes.

Any suggestions on how to fix this?

I have to give iNdependence props and all, but they could have at least built in the bsd subsystem, or installer.app by default into the jailbreak