Right click the sheet tab and select View Code.
Delete anything that is in the window. Then add something along the lines of
Private Sub Worksheet_Change(ByVal Target As Excel.Range)
If Target.Address(False, False) = "F50" Or Target.Address(False, False) = "F100" Or Target.Address(False, False) = "F150" Then
This will print the whole sheet. You may wish to modify this to print only the last 50 rows. The easiest way to determine how to do this is to record a macro to see how to set the print area.
Hope this gets you started.