I'm working on that right now on my non-flying kit, but flying or not makes no difference for this. The 5th-point kit from Vans won't fit the RV-6 without modification. However, their kit is a good starting point. If you buy the RV-7 harness kit you can just cut off one side of the braket they provide and rivet on some angle to adjust the width to match your seat rib spacing.
As always, there are many other ways to get this done, but that would probably be the most straightforward since there is hardware and instructions included.
It's actually a pretty easy retrofit using the Vans kit for the -7. I followed the advice of some others on this site recently and just cut one of the flanges off and made my own flange to fit the seat rib spacing.
It's actually a pretty easy retrofit using the Vans kit for the -7. I followed the advice of some others on this site recently and just cut one of the flanges off and made my own, new flange, to fit the seat rib spacing.