Here you go!
This should get you started. You'll need to edit the composer.tpl, or inject html at composer load, checking if the post is a new topic.
The birthdate field looks like it wants
However, it's not possible to type dashes, and using the date selector fills in using
mm/dd/yyyy format. My age shows correctly in my profile, so I guess the placeholder text is just outdated.
Also in the topic listing, I move my mouse to the left white space so I can read the topic names, but it crosses over an avatar temporarily and suddenly a usercard is permanently obscuring topic names, and I have to move my mouse all over the place until it goes away (it stays forever if I leave my mouse in the white area on the left)