Have you checked the Applications folder to see if LW is installed and if it is possible to launch it?

If it will not launch, try a safe boot before reinstalling. ie: Hold the Shift-Key down as you are booting up. (I think MacBooks can be safe-booted.) A safe-boot often takes longer than a standard boot.

Which version of LW 5 are you installing? Chances are I can probably host a ready installed package. To my knowledge, LW is no different to most other program packages, all is inclusive within the program package itself except for user settings. LW does not depend on plug-ins, shared libraries, etc. outside of the program package to my knowledge. Only external dependency is a Java environment.

Edit: I reinstalled LPE. The only file in the program package to show a change of date is the LimeWire.jar file. Other than this, there is a Install LimeWire.pkg file installed into the Receipts folder of the system's Library folder and install listing noted for program identification in InstallHistory.plist in same folder. In your case the script must have failed achieving one of these functions.