The easiest way would be to store the request URL in a cell somewhere and interrogate this in your macro. A cell could contain the URL and a separate named cell a formula which returns 1 or 0 depending on whether to run the macro. e.g. =IF(A1="http://www.google.com", 1, 0). The cell could be named "blrun" for example.
In the macro, you then add the conditional statement.
VBA Code:
If Range("blrun") = 1 Then 'run the routine Else Exit Sub End If
