OK i think i did it... i will try to explain how you register it as simply as possible.
You first install the 3.5 version. You then replace the SelectRadio.exe with the SelectRadio_key.exe (after first rename it to SelectRadio.exe of course).
When it runs, in one of the first screens, it shows you the correct registration number for your machine id. You have to note that number you will need it....!
It will be a 16 digit number.
You then install the 4.5.1 file from the ppc which installs the new version of the selectradio and when you run this and it asks you for the registration number you enter the valid number the previous version gave you.
You then restart the program as it asks you to do and you are done!
I hope i was clear enough...if you have any queries don't hesitate to ask
I tested, and it ok. if you have any queries don't hesitate to ask