With difficulty. You'll have to ballast/shim underneath the scale track to get the rail heads level and devise a means to keep the rails in alignment. Other than solder, there are no transition fittings to connect the rails together.
I have read recommendations to grind a tubular pin form factor in the ends of scale track rails and plug into tubular (or a RealTrack transition section). After building turntables and lift gates, I feel keeping alignment of unjoined track is simpler than grinding.