If you have the Palm Desktop installation CD, you should re-install the software and let Palm Desktop place the conduits in their proper places. I'll give you instructions based on my memories of how this works. It's been a while since I had to do all this. If you don't have the CD, look on the PalmOne website for Mac OS X Palm Desktop software and download it from there.
I'd uninstall the current Palm Desktop first, however, to remove any potential beasties. Insert the CD into your computer, go through the installation motions until you get to the part where it asks you what kind od installation you want. The choices should be "Easy Install", "Custom Install" and "Uninstall." Choose the latter. It may ask you where the Palm software is, if so point it to the "Palm" folder in the "Applications" folder. Hit OK.
When that's done, I'd restart the computer, and when it's done re-booting run the Palm Install CD again, go through the installation motions and this time choose "Easy Install." It might ask you where you want to install the "Palm" software, and if it does just point it to the "Applications" folder.
When that's completed, I'd restart the computer again (I like having things settle into order with a clean restart) and then I'd connect the T|3 and perform a HotSync. It might ask if you want to create a user based on your current T|3 user profile, and if so say "Yes."
The HotSync process should go smoothly, if not long-ly. (?) The first HotSync will take a long time because it's writing all of the data from your T|3 to the Palm Desktop for the first time. Subsequent HotSyncs should be quicker.
You might have to re-install any third party conduits if you had them previously (ie, Vindigo, AvantGo,... although I doubt you had AG since they cancelled their OS X support...) If so, that should be easy.
Hopefully the process is relatively painless and that you can get all of your data back to normal. Let us know how it works for you.
POL9A