You can't -- it's a security measure that protects your password and your computer. In college, incorrigible students would log on to lab computers and display fake logon screens. When other students would sit down and log on to the computer, the screen would flash and their password would be stashed away for later use; but, the student would never know that their password had been scraped. CTRL+ALT+DEL protects you from that scam as well as others.
This was first published in November 2002