Sting's Thumb / Index Finger Technique

[Delberthot]

I find myself using my thumb more and more for tunes with one of my bands and want to learn how to play like sting does but can't find anything to show me how it is done.

Lets face it - it looks cool and is completely different to normal. I have only ever seen one other bass player play like this.

I am fully versed in "regular" 2 fingered playing and just want to add something different to my repertoire.

Any sources of info are fully appreciated.