If you use the default email setup process on the TP2, it will automatically find the settings for Yahoo mail,
but they may only work for a short period of time (see my post here) or may not work at all. For some, it may actually continue working, but for both my wife and I, it only worked for a couple weeks before we started getting connection errors.
If you have Yahoo! Mail Plus, you can configure POP access to your account, but you will need to trick your TP2 into bypassing the automatic "search for settings" feature. To accomplish this, simply start the email setup process, but enter a bogus email address at the start (e.g. you can use something like
emailid@yahoob.com). This will allow you to enter the manual config screens where you can specify POP access and use the information
here).
Hope this helps. If you don't pay for Yahoo! Mail Plus, I'm not sure what your options are (sorry).