You indicated in the other post you installed the updated Palm Desktop and you should have a Quick Install feature too:
Installing applications from a Windows computer
1. Drag and drop the file(s) onto the palmOne Quick
Install icon on the Windows desktop.
2. Select your username from the list, and then click OK.
3. Synchronize your phone with your computer to install
the application(s) on your Treo smartphone.
If you did not get a User Guide with your Treo I urge you to download the correct version from Palm's website. There is a wealth of information in it.
Visit
this link and scroll down to find the proper carrier version and you will keep yourself busy for hours exploring all that you can do even without a data plan to connect to the Internet.
You might also look into using a card reader on your PC. Download the Palm program to the SD card, place the card in your Treo and install from the card.
Keep in mind that some programs can be installed to the card and run from there and others require installation to the Treo device.
That should also be covered in the manual.
Bluetooth using another phone as a modem? Doubtful, but who knows. There are just easier ways to do it....
SteveTaz