INT 2C P - Cloaking - SET SEGMENT ACCESS MODE                                   
	AX = 0004h
	SI = selector
	CL = new access mode byte (see #00502)
Return: CF clear if successful
	CF set on error
	    AX = error code (see #02556)
Note:	this function was first introduced with RM386 (RAM-MAN/386) v6.00
SeeAlso: AX=0000h,AX=0002h,AX=0003h,AX=0005h,INT 31/AX=0009h