*DO THIS AT YOUR OWN RISK*
You will need ADB, to know what it is, follow this LINK.
You will also need this file.
Once you have ADB and have downloaded the file above, connect your phone in USB debugging mode to your computer and run ADB in the windows command prompt.
adb shell mount -o rw,remount /dev/stl12 /system
adb shell mv /system/bin/wpa_supplicant /system/bin/wpa_supplicant_original
adb push wpa_supplicant_adhoc /system/bin/
adb shell chmod 755 /system/bin/wpa_supplicant_adhoc
adb shell busybox ln -s /system/bin/wpa_supplicant_adhoc /system/bin/wpa_supplicant
You can also share your internet connection through your ad hoc network by enabling network sharing when you set-up your ad hoc. :)