Registering at UPS to use their shipping rates calculator is a two step process 

STEP ONE:

First go through the Registration pages. Click Here

After you register you will need to login, Once you log in you will need to select the tool you are registering. Scroll down to the section called:

UPS Rates & Service Selection
The UPS Rates & Service Selection tool returns rates for available UPS domestic and international services, and provides UPS published shipping rates.

Click the "Get Tools" Link.
This will bring you to a "License the Tools Page". Click the "Go to end user license agreement link. Scroll through the License agreement, reading would be good :) then click the "I Agree" button.

This will bring you to a page Called "Before we issue your License" Page. Make sure all the BOLD fields are filled in correctly then submit the form. You are now registered and UPS will send you an email with a Developers Key in it.

STEP TWO:

After you receive your Developers Key, you will need to get an Access Key.

Click Here Get Access Key
then on that page click the Get XML Access Key

Insert your Developers Key from the first email into the box provided and click Submit.

The next page is a "Users Terms" Page, scroll down (reading would be good :) ) and click the "Yes I agree" Button.

You will again be directed to a page to make sure your user information is correct.

After you submit this form you will receive a page that will have your Access License Key, as well as receive an email with the key in it.

After you get this key you can enter it and your username and Password that you submitted to UPS in the Stores "Shipping Setup" Page.