It's not in Preware and it isn't a setting in Screen & Lock. I tried to convert this patch to work on the TouchPad about a month ago. I'm pretty sure I got it right but it never would work. I'm not so sure TouchPad uses the file that this patch edits anymore. I'm thinking it might be in C+ or whatever like the top bar and launcher where you can't easily edit it.
I whipped up a patch using the file attached in post 1 and the original file. I did remove the vibration from this, and added a check to make sure that we weren't going to check the password when there is a limit to the number of attempts you can make.
Did you know:
webOS ran on a Treo 800 during initial development.