Oil finishes

Neil Ellis in his 'Polishers Handbook' which I have used to great advantage says that various oil finishes can be applied (especially large areas) with an orbital sander which handily also heats up the oil and helps it harden and work into the timber. He also mentions that one should (obviously) use wet and dry through grades as high as 1500.
With a large table top to finish I find that the discs for orbital sanders do not come in wet and dry for any brand that I can find nor do they go above 400 grit,
Am I reduced to heating the oil and hand sanding or can anyone, especially Neil, advise where I can get orbital sander discs in wet and dry and something up to 1500 grit. Naturally these all fit on with a velcro backing so one cannot simply buy sheets of wet and dry and fir them onto the sander.
Aslo, is there a good hardening agent I can safely add to say Danish oil to give and even harder surface to the table which wilol probably be made from river gum?
HELP???!!!

I've not seen W&D with velcro; have seen Organoil applied with ROS presumably just with standard furry backed quality paper.

Re hardening of DO: I don't think you need to worry ... just keep building up layers following instructions carefully. From memory its just poly and oil; the oil will 'go off' and harden by itself if you just give it time.