hey MysteryGuest,
To emulate human behavior, you need to hook the keyboard and mouse directly to your bot. This means your bot can't lose focus and can't use any other program at the same time.
If you are planning to use SendMessage or PostMessage, it doesn't work unless you also trigger the Javascript events on the web document as well.
Google tracks every single keystroke and mouse click, so you need to set your "typing" timer between 300-600ms for each keystoke.
And then comes the fingerprints.. google tracks everything, from your browser, system, screen resolution, flash version, plugins installed..and even the fonts you are using.
You'll need to spoof all those, possible, but it's a big job.
Even then it's no guarantee that google won't pick up something and ask for verification.
Sometimes it's just easier to just verify without trying too hard to fight them.
That said, if you can make a bot under $30..it will sell extremely well. Just hope it doesn't stop working after 3 weeks.