1.Duplicate the track with the event which you want apply the LUT to.
2. Apply to upper track, leave the below one as the original. If you are applying LUT to the whole frame, skip to #7.
3. If you want the LUT to be applied only to a specific part of your image, use mask in the Event Pan-Crop control, switch on the "apply to FX" mode (read help).
4. Animate mask with key-frames manually, or use a "pixel chooser", or a planar tracker (you'll have to purchase a plugin, there is a choice).
6. If you need a different LUT for a different area, or if you want to have more than one LUT applied (must be funny), duplicate the original track more than once. Always leave the untouched original as bottom-most track.
7. Using the Composite Level slider of the track control to the left, adjust the extent to which the upper "LUTed" track affects the original. You may change the "LUTed" track composite mode to, say, "add", "subtract", "lighten", etc. (read help).
8. You may vary the extent of "LUTness" within the duration of color-corrected clip, using the track's Composite Level envelope.
Vegas is not just an NLE. It is a (nearly)-complete post-production house on a laptop.