Ok the script can't be turned into a plugin but it can still have custom attributes to control the values.
I've got one more bug to iron out and bingo.
I have made quite a few other changes to the script but............ it seems someone else is about to release the same thing quicker than I can soooooo, I'm finishing the script but wont be uploading it to scriptspot as there is no need for two scripts that do the same thing. Once finished I'll be moving on to another script similar in function that will make creating procedural objects a lot quicker.
I won't be uploading it until I've completed it this time as someone else will just pinch the idea and beat me to it.
Stay tuned but don't hold your breath!
Ps Thanks to Håvard Schei for all his help and advice