Private Sub Text1_KeyDown(KeyCode As Integer, Shift As Integer)
   If KeyCode = vbKeyF6 Then
       Me.Text1.VALUE = DATE
   End If
End Sub

This will do this for the specific field when it has focus

to do this at a form level you need to set the "Key Preview" property for
the form to yes and set the event handler for the form for KeyDown event

Another alternative is to create an AutoKeys macro.

For more information, check this link or the help file.

http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/office97/html/m
akingkeyassignments.asp

BTW, there is an inbuilt shortcut ket for today's date already. It is CTRL +
;