I looked at it after my problems and you need access to both the inside and outside of the tube which means opening up a seam to get in, you cut a hole, shove it through and then there is a sort of nut thing which screws onto the inside of the valve to clamp it IIRC. I suppose you could fit the valve to a big patch and then glue that onto the deflated tube but I should think that clamping it to make sure the glue was attached properly, might be easier said than done...
After my efforts at repair and having got an airtight boat I decided not to make any more holes in perfectly serviceable chambers - however my 2 inner sausages have PRV's fitted - by Mr Tilley
I wouldn't buy another RIB without them though, and I can't understand - for the minimal extra cost - why all manufacturers don't fit them to all boats and tubes as standard.