How to set PAL-Flag in NSF-Header?

Here's an overview of the header:

offset  # of bytes   Function
----------------------------
007a    1   BYTE    PAL/NTSC bits:
                 bit 0: if clear, this is an NTSC tune
                 bit 0: if set, this is a PAL tune
                 bit 1: if set, this is a dual PAL/NTSC tune
                 bits 2-7: not used. they *must* be 0