Meta's Llama3-405B is a large language model that represents a new frontier in open-source models, offering capabilities rivaling top closed-source AI models. However, its size and computational requirements make it daunting to run. To overcome this, the guide outlines optimizations such as 8-bit quantization, multi-GPU setup, and reduced VRAM footprint. The process involves creating an account at modal.com, installing the Modal Python package, authenticating the account, and using three separate files from the provided gist: downloading the model weights, setting up the vLLM server, and interacting with the model. The guide also provides options for customization when interacting with the model, such as adjusting generation parameters or providing a custom prompt.