UPS provides a free software for all UPS customers called WorldShip. This application is optimized for printing labels in 4 x 6 format in high-speed and with efficiency. UPS.com website, on the other hand, has more limitations. Please see this article for setting up WorldShip with Rollo.
If you don't like using WorldShip, we then recommend one of the commercial solutions discussed in this article. They connect to UPS.com and print your label in 4 x 6 format using your negotiated rates for your shipments. They are online, user-friendly, and you can set them up in just a few minutes.
If you definitely want to ship from UPS.com directly, then there are two ways to print from UPS.com:
1) You may leave the settings as default on UPS.com and crop the label using steps in this article.
2) One of our customers and a mathematics professor has created a software to make this process easy: http://www.sroman.com/Software/index.php
3) Install Rollo as a UPS Thermal Printer. Please note UPS.com Thermal Printers only print to 4 x 8 (not 4 x 6) label sizes so please ensure you have the correct label. This size limitation does not exist with UPS WorldShip or Commercial Solutions as discussed above. To install UPS Thermal Printer, please follow this guide from UPS and install Rollo as UPS Thermal 2844 printer.