Your post isn't quite clear. Are you dealing with a touch screen? If not, then I don't get the question. If a form field has the focus, you can enter any digits simply by using the pc keyboard.
Or are you saying you want a keypad type of form that looks like the calendar control, in which case, I can only imagine that you are using a touch screen.
EDIT: I just had to try interacting with an Access command button with my laptop touch screen. I never knew, but WOW it works. So I guess you'd build a form for this. Opening it would have to be via first touching the control where you want the data to go. I suppose the Got Focus event would be the one to open the form, and you'd pass the control name to the keypad form Open Args so it would know where to place the number(s). If you opened that form in form view via the nav pane, you'd need to trap for that. I also guess that you could either assemble the entire entry then transpose it to the form, or do it one digit at a time. With one at a time, you'd have to provide back spacing. Either way, a test for existing data would need to highlight that entry so it could be replaced with the first press of your keypad form buttons. Seems quite intriguing.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.