How would I force Debian to use the physical sector size on a hard disk?

According to an interview with a Western Digital representative published on http://www.techarp.com/showarticle.aspx?artno=734 there is no option to disable 512e emulation on current Advanced Format drives.

[...] will Western Digital offer firmware upgrades that would convert current Advanced Format drives running in emulation mode, to the native format?

Unfortunately, no. Current Advanced Format drives cannot be converted to run in the native format through a firmware upgrade