As other already have said, you can scan main and sub band at the same time.
Just remember one thing thought.
If main and sub end up receiving the same signal on different frequencies, you get an ugly beeping sound.
As to programming the unit. I went the easy way.... I asked Alinco in japan for help.
They provided me with some nice specs, from which I created an Excel-Sheet to feed my scanner with.
I can programm different memory locations, and change the bank-layout from 1 bank with 1200 channels to 50 banks with 24 channels. Or anything inbetween, as long as I end up with 1200 Channels.
Unfortunately the ERW8 doesn't play nice with my Win7 laptop, just my MacBookPro.
It's not perfect, but easier than with the Alinco software for sure. Especially when trying to enter more than 5 frequencies.
Ralph