Mine also shows 64 bit kernel and extensions as "NO" Tried the "4" and "6" on booting and it didn't work, then tried editing the file you mentioned and osx wont let me save it. Any suggestions?
Thanks.
You didn't say what kind of Mac you had. And to try to force it to boot into the 64-bit kernel after it wouldn't boot into it using the 6+4 keys is unadvisable.
If the 64-bit kernel won't load after holding down the 6+4 keys on boot your system is not compatible with the 64-bit kernel.