change white balance in PSE10 to a jpg - possible?

silly questioin i guess but...

when i load a raw file from my d300 (NEF) into elements 10

ACR opens up as it should and there is an eye dropper to set a white balance from a target. all well and good.

BUT....

if i open a jpg can i set the white balance in pse10? or is this only sensible/allowed/possible in ACR on raw files?

thanks