Put something like this in the workbook code area:
Private Sub Workbook_BeforePrint(Cancel As Boolean)
v = ThisWorkbook.CustomDocumentProperties("lab1").Value
ActiveSheet.PageSetup.CenterHeader = v
End Sub
Replace "lab1" with the name of your custom property. Because it is
workbook code, it is very easy to install and use:
1. right-click the tiny Excel icon just to the left of File on the Menu Bar
2. select View Code - this brings up a VBE window
3. paste the stuff in and close the VBE window
If you save the workbook, the macro will be saved with it.
To remove the macro:
1. bring up the VBE windows as above
2. clear the code out
3. close the VBE window
To learn more about macros in general, see:
http://www.mvps.org/dmcritchie/excel/getstarted.htm
To learn more about Event Macros (workbook code), see:
http://www.mvps.org/dmcritchie/excel/event.htm