As the previous reply stated, you can't. You can however do something like;
make the checkbox a text box looks like a checkbox, sunken with whitebackground, font = arial, 8, bold.
In properties, make the name = txtCheckBox
Then assign the following code the the click event;
Private Sub txtCheckBox_Click()
If Me!txtCheckBox.Value = "X" Then
Me!txtCheckBox.Value = ""
Else
Me!txtCheckBox.Value = "X"
End If
' goto next control or whatever...
' DoCmd.GoToControl "your Next Control"
End Sub
So when user clicks, it will toggle display of X and "".
You can then interrogate .Value.