If you want to do this with the RAAL covering most of the high end you'll need a conventional crossover with a minimum of a 2nd order electrical filter on the RAAL, which would mostly defeat the purpose the speaker... you'd probably be better off using a different driver or cutting the whizzer off the Omega driver, which would be very scary as Alnico drivers aren't cheap.
One way you could do this is to cross over very high (~10k) 1st order and run the tweeter facing back as CR recommended, but you need a minimum of 4' and even better 6' placement from the back wall. Another option is to face the tweeter up towards the ceiling, possibly with the tweeter behind the speaker and located near the floor to maximize path length.
If you do the rear or upfiring configuration with a high crossover point you may like the results... just don't try to face the RAAL forward and have it combine with the whizzer, that probably will not work well.
If you try it let us know how it goes!