I just purchased the HiTechnic Barometer from LEGO, thinking the Block was available for the EV3. Theory says that I can use NXT Block in the EV3. Can anyone point me in the right direction?
I'm not sure where you got your theory, but no NXT blocks will not work in EV3 software.
You may be able to use this with the LEGO EV3 software using the generic I2C block developed by Dexter Industries.