That's trickier. You will have to manually output the input.
What I mean is to not use the INPUT command and to use WAITKEY command (I hope that's the right command, I can't check, I'm at work) to get keypresses from the user and then TEXT that keypress to the screen so the user can see it.
You will have to use a variable to keep track of where to TEXT the next keypress each time and increment that variable each keypress.
You will also have to check for the enter key and backspace key (and maybe even the arrow keys if you want to give the user that much flexibility).
Of course, you will have to decrement the variable if the user presses the backspace key.
What I mean is to not use the INPUT command and to use WAITKEY command (I hope that's the right command, I can't check, I'm at work) to get keypresses from the user and then TEXT that keypress to the screen so the user can see it.
You will have to use a variable to keep track of where to TEXT the next keypress each time and increment that variable each keypress.
You will also have to check for the enter key and backspace key (and maybe even the arrow keys if you want to give the user that much flexibility).
Of course, you will have to decrement the variable if the user presses the backspace key.