How can I use this square cursor ( image below ) in the input tags ?

For tags, there's not much you can do. If you didn't mind it being a horrible hack, you could always use JavaScript to resize the text box as needed (set width = *something* * count), and have an with the cursor to the right.
I don't think there are any less 'ugh' solutions, bar handling the text input yourself, which is probably overkill.