How To:
Enter the title of the link (anything you choose), choose the car, & circuit, then set the weather conditions for the session you want to emulate, you can find them in the upcoming schedule section of the iRacing website (Race Now > Schedule > Sessions > Choose Your Date).

Click to generate the link, then simply drag the link ^^above^^ onto your bookmarks toolbar.

Go go to your iRacing Member Home Page, & click on the "TEST" button

Click the new shortcut you just made on your toolbar & you will see the car, circuit, configuration & weather settings change. Done!

Generate as many links as you like & keep them on your bookmarks bar or add them to your favourites folder.