With CSS you can basically change font and size:
<input style="font-size:18px;width:85px;font-family:Lucida Console" type="password">
but it is unpredictable what will happen from browser to browser. What you can do is use a custom font, however, nothing guarantees that the browser will actually use it in practice.
The alternative would be to use Javascript to swap the characters of a text field, however, there are several security issues involved.
See some tests on JS Fiddle, remembering that after you manage to leave exactly the way you want, will test in another browser and... bam! Surprise, everything different!
But they are already WELL different from browser to browser. It will get a little complicated.
– Bacco