Call any Volvo shops, i believe can be added; my dash shows both steer and drive pressure; I pick up lots of preloaded trailers and is very useful to get on idea about the weight; if shows over 58-60 psi/drive axle, i know i'm close to limit 34,000 lbs/ drives and have to scale the load.
I dont know if the feature can b added , my inpresion is yes , because i have couple friends of mine that own 07'780's like mine but theyr trucks dont have tha same cluster features , and i dont think that Volvo changed cluster design in midle of the year 07