INT 67 - RM386 - SET PAGE TABLE BITS FOR RANGE OF PAGES                         
	AX = 5DE7h
	BL = page table bits to be set (bits 2-0 = U/S, R/W, P)
	CX = number of pages to set
	DX = first page number to set (in first megabyte)
Return: AH = status
	    00h successful
	    8Bh invalid destination page (not in first megabyte)
	    A5h invalid page bits
	    A6h invalid page count (overflows first megabyte)
Note:	RM386 traps this function on the initial transition to protected
	  mode caused by the INT instruction, which means it can not be
	  overridden simply by hooking the interrupt