Sets the BLF_CUSTOMEXT flag. Sets the value of the 'Use Custom Extension' checkbox.
EnableCustomExtension(pBlackIceDEVMODE As Long) As Boolean
Input value - handle to the BlackIceDEVMODE.
Return value - TRUE if the flag was successfully set, otherwise FALSE.
NOTE: For 32-bit applications , use pBlackIceDEVMODE as Integer, instead of Long.