MultiMC has built-in support for LiteLoader and installing LiteLoader is extremely simple. To add LiteLoader to a MultiMC instance, take the following steps:

• Click the Edit Instance button to show the instance editor dialogue
• Click the Install LiteLoader button, you will be presented with a dialogue showing the available versions
• LiteLoader will appear in the list, indicating it was installed successfully

That's it! LiteLoader is now installed successfully with MultiMC.