script to write 1's and zero's for cell color

Seeing as you are using Excel 2007 and it allows filtering by color, you can script this.
Here is an example you can build on:

Note: you will need to determine the RGB value of the cell color, which can be done by simply activating the cell and calling up the color pallet via Format Cells. If you have multiple cell colors then you will need multiple passes to accomplish.

Using the specialcells method will be much faster than looping through 600K cells.

Option Explicit

Sub Check_Cell_Color()

    Application.ScreenUpdating = False
    
    With Sheet1
        If .AutoFilterMode = True Then .AutoFilterMode = False
        .Range("B1:B600000").AutoFilter Field:=1, Criteria1:=RGB(242, 242, 242), Operator:=xlFilterCellColor
        .Range("Z1:Z600000").SpecialCells(xlCellTypeVisible).Value = 1
        .AutoFilterMode = False
        .Range("B1:A600000").AutoFilter Field:=1, Operator:=xlFilterNoFill
        .Range("Z1:Z600000").SpecialCells(xlCellTypeVisible).Value = 0
        .AutoFilterMode = False
    End With
    
    Application.ScreenUpdating = False

End Sub