I don’t own one, but from a little reading …
A) Looking at the spec sheet, the drive requires 12VDC … so, it’s not gonna work with a “self powered enclosure” (you’ll need to buy an external AC powered enclosure)
http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-800002.pdf
Looking at the spec sheet again …the 750GB & 1TB may work with a self powered USB (5VDC)
B) My WDTV sees the entire 3TB of my WD MyBook
i don’t know if the WDTV will see the entire 6TB of a Red Drive … you may have to create 2x partitions (3TB x 3TB)
Anyways … if someone owns a 6TB Red HDD, please post your experiences here