I know two mods actually use the "maxmotives" command are Awesome Mod and Twallan's Super Computer.
Awesome Mod is a core package that changes the way the game is run and how you play the game. Pescado added that command to AM so that you can maximize your Sims' needs. You can find it
here. Read the instructions on how to install AM.
But if you didn't want a core package like Awesome Mod, you can look at Twallan's Super Computer as an alternative. You can find it
here. The pie menu is available on either the Sim you want to maximize the motives on or on the computer. The instructions are fairly clear and there is a very good list of options available to do specific things.
I use both AM and Twallan's Super Computer without a problem. But if you have questions about either one, please post them at the appropriate site.