OK. My contribution. I did further research after my earlier post. And also did further experimentation after getting the Datel transfer kit as well as the xplorer360 software from 360gamesaves.com.
Long story short - we can't import existing WE9 option files to the 360 as backward compatible game saves will only work when it's on the 360's hard disk and not memory unit. Also, backward compatible game saves cannot be transferred from memory unit to 360's hdd and vice versa.
The only solution as of now:
(1) either dissect your 360's hdd and connect to your pc via the technique shown on 360gamesaves.com and copy the option file over from pc to hdd using xplorer360 (copy to partition3/compatibility/xbox1/udata folder); or
(2) if you're a pussy like me when it comes to removing the 360's hdd from its casing, then wait for an external adapter like the ones the guys at 360sata.com are mass producing, plug that to your pc's usb, and use xplorer360 to copy the option file over to the 360's hdd.
Hope that helps.