You could try something like this. Although personally, I don't like password protected buttons. I would make the button Enabled = False then make it enabled when the correct user's name is entered. You could pick up the user's name from their login. I am assuming you can pick up the user's name fronm the system.
Code:
'***************** Code Start ***************
Private Sub cmdOpenEmpForm_Click()
'Attached to On Click event of cmdOpenEmpForm
Dim strPasswd
strPasswd = InputBox("Enter Password", "Restricted Form")
'Check to see if there is any entry made to input box, or if
'cancel button is pressed. If no entry made then exit sub.
If strPasswd = "" Or strPasswd = Empty Then
MsgBox "No Input Provided", vbInformation, "Required Data"
Exit Sub
End If
'If correct password is entered open Employees form
'If incorrect password entered give message and exit sub
If strPasswd = "Graham" Then
DoCmd.OpenForm "frmEmp", acNormal
Else
MsgBox "Sorry, you do not have access to this form", _
vbOKOnly, "Important Information"
Exit Sub
End If
End Sub
'***************** Code End ***************