I know this is a really really old thread but I recently encountered this annoyance (lack of functionality for the middle mouse button in premiere) in PR CS5.5 and after searching for a solution I decided to write my own script that emulates the AE behaviour.
It’s written in AutoHotkey. Provided source code and compiled Exe. If you’re concerned about the .exe, just save the source code as something.ahk (you need AutoHotkey installed, you can also compile it yourself into an exe afterwards).
It only works if Premiere window is active (it searches for the window name). Once you click the middle mouse button, the script pushes the H key and replaces the Middle button with the Left button. Once you let go of the middle mouse button, the script pushes the V key and lets go of the Left click.
TL;DR It switches between the select tool and the hand tool. Works exactly like AE middle mouse button.