You still can! Here is what I wrote about this in a
different thread:
When I first changed the default camera button from the default camera to Nokia Pro Cam, I noticed that pressing the camera button from sleep mode to awake always made me input my 4-digit password, whereas previously the default camera app did not make me do this. I went back into the Settings > Applications > photos+camera and checked "Prevent accidental camera launch when phone is locked" and now it works where I can bypass the password and go straight from sleep to the Pro Cam app (I know, the wording of that and what it did sounds counterintuitive, doesn't it?).