If you are using ENVI 4.4, you can toggle the option off in the ENVI Preferences. This option can be found under the Miscellaneous tab and its called 'Auto-Correct ASTER/MODIS'. If you have an earlier version of ENVI, you will need to open the file as Generic HDF and select the datasets you wish to open. This of course will not read all the metadata of the file like the custom reader in ENVI does, so you will have to populate the Map Info yourself and perhaps other things such as Wavelength in the ENVI Header.