I've built a simple python app (my first one ever by the way, yay! ) that will take the lockslider picture and place another picture over it, which i then write the number of missed calls and text messages based on nex's code (see above). It then saves all this as an image "lockslider.png" in the same folder. So if we can place the script in the theme folder and run it when an sms or call is recieved it will update the lockslider image with the new information. I'll try post it soon, but i'm currently at work with no cable (and mobile internet here is expensive )

All thats needed now is running the script when needed