My Book Essential 2TB USB3 head parking

Hello, yesterday i bought WD My Book Essential 2TB USB3 and the drive inside is Caviar Green WD20EARX Sata III (readed through Aida64), and the drive park his head every 8 sec (which i think is the default time for the green drives). But wdidle3 doesn’t seem to support external drives, so is there a way to change this time or the only way is to open the case and connect the HDD  with SATA cable, avoiding the warranty - which i don’t want to do?

Thank you.

I had a My Book for a while an I haven had to mess with settings like that

this drives are ideal for external drives due to the low power consumption