Not sure what you mean about the auto-entered part. If the UBB knew who the user trying to log in was, it wouldn't need them to log in!
To set focus to the username box, append the body tag in public_login.pl with:
onload="javascript:form.username.focus();"
and append the form tag in that file with:
name="form"
that should do it, I think... untested.
[ 09-17-2001: Message edited by: Borg ]