I think I got it.
I understood it in a very wrong direction. I thought I could use the mixer song channels to select my instruments prior to recording. It's totally different from the style creator. Voices are used via the usual registration memory buttons or even the OTS buttons since a song channel is reading the voice directly from a part (R1,L,R2,R3). After recording, I can use the mixer song channels to modify, mix, pan, and master when necessary.
Honestly, I find MIDI recording in DAW is much much more better. Sequencer in Genos is very weak and it takes time to get used to it. Tracking colors in DAW is very important to me and my work. The flexibility to cut, copy, modify, delete notes is incomparable in DAW. Even though I can do this in step recording in Genos, it's still a slow process.
Looks like I am going to skip recoding MIDI in Genos and do it the flexible way.
Thanks John, my question is answered.