Progress indicator for macro that loops through each worksheet

Hi all,

Thanks in advance for any help.

I have a macro that goes through each worksheet and clears all of the unlocked cells (sets their value to "").

Sub ClearUnlockedCells()
Application.ScreenUpdating = False
Dim sh As Worksheet
Dim cell As Range
For Each sh In ThisWorkbook.Sheets
For Each cell In sh.UsedRange
If cell.Locked = False Then cell.Value = ""
Next
Next
Application.ScreenUpdating = True
End Sub

This macro takes a while to run so I'd like to add in a progress indicator. I've found a lot of examples for how to build one using a Userform (such as http://spreadsheetpage.com/index.php...ress_indicator[/HTML]) but I can't figure out how to connect the progress indicator to the actual progress of my macro. I'm quite new to VBA so forgive me if this is really simple.

Cheers
Gareth