Since the last release, I've made changes to Ben Kenobi, AOTC Padme, Darth Vader's face, most of the character pictures that you see before the main menu, the pizzas in Ruin of the Jedi, and a few other things. I just can't stop tinkering with it.
Extract the uMod folder and Lego Star Wars.tpf to a convenient location (I have them inside the Lego Star Wars Saga game folder).
Run uMod.exe in the uMod folder.
In the menu called "main," make sure that "use global hook" is checked, then click "add game."
Locate and select LEGOStarWarsSaga.exe.
Launch LEGO Star Wars: The Complete Saga with uMod still running.
Once the game has launched, use alt+tab to switch back to uMod.
Click "Open texture/package" and select Lego Star Wars.tpf. Click "update" to activate the package. Additional packages can be activated in the same way.
In the "main" menu, click "save template as" and save your template.
Click "set template as default" and the game will always launch with my texture pack enabled as long as you launch uMod first.
You'll know it's working if the splash screen shows the Disney and Lucasfilm logos in place of the Lucasarts logo.
If you've been using Texmod and prefer it to uMod, you may of course continue using it.