No. JK's driver AIUI works by patching the OS's graphics routines directly. The ROL driver uses the abstraction interface provided. The video layer in RO6 works quite differently and the code is in totally different places. The reason that OS6 kills the original VF driver on startup is simply that if the original driver manages to initialise on RO6, it stiffs the machine completely. Of course this happens way before you get to the *command prompt, so it kind of renders the machine unusable .
I'm doubtful of the benefits for the workload involved of updating the R128 driver (given one exists) nor for the Mach64 (given its obsolescence), but I'm sure John could write a very nice video driver for RO6 for the Radeon if there was interest - with the added benefits discussed earlier in the thread .