So you are writing to a 8 bit port.
Let us assume
CLK = 1,LSB
DOUT = 2
LATCH = 4
OE = 8
DIN = ignored

And OE and Latch are active low.(??)

This means it is safe to write data while to clock is high or low

Write to port &HF to init port to 1's

Enable Chip, Write to port &H7
call writeByte(HighByte)
call writeByte(LowByte)
Latch, Write to port &H3  
disable Chip, Write to port &HF

sub writeByte(Byte)
   For X = 0 to 7
      if Byte and &H80 Temp = &H2  'send a 1
      else             Temp = &H0  'send a 0
      Write to port Temp AND &H5   'send bit to port, clk and latch high 
      Byte = Byte * 8              'Shift Byte Left

      Write to port Temp AND &H4   'Clock Low
      'May need a delay here
      Write to port Temp AND &H5   'Clock High (and Data transfers)

   Next X
end sub

This be good for a start check the data sheet to be sure about latch and OE