Option Explicit

Sub Setup_OnKey()
    Application.OnKey "{PgDn}", "PgDn_Sub"
    Application.OnKey "{PgUp}", "PgUp_Sub"
    MsgBox "PgUp and PgDown have been re-mapped."
End Sub

Sub Cancel_OnKey()
    Application.OnKey "{PgDn}"
    Application.OnKey "{PgUp}"
    MsgBox "PgUp and PgDown have been restored to normal."
End Sub

Sub PgDn_Sub()
    On Error Resume Next
    ActiveCell.Offset(1, 0).Activate
End Sub

Sub PgUp_Sub()
    On Error Resume Next
    ActiveCell.Offset(-1, 0).Activate
End Sub