Simox, many thanks for the advice - it works a treat. I had my doubts that it could be that simple which is why I asked.

I have used the first option of directly editing the original Customize.xml file (yes, I have a back up) and reloaded it to my phone. I am now able to set the right Nav Pad shortcut to anything I like -such as Opera Mini.

Once again, many thanks for confirming that it really is that simple. :)