You can use ExifWrite feature of ExifMeta (a free plugin I wrote), to update capture time - you specify a base time, and each selected photo will be assigned that time plus an offset which depends on it's position in the grid. Here is a cut from the UI:
John Beardy also has a plugin that will do it.
Thanks so much! You made my day - and saved me a few probably
What does the 1st option in this menu do, I wonder? Never used it.
It copies all exif metadata from your source file(s) to your catalog, making it available for lib filtering, smart collections, viewing, etc...
Lightroom only supports a subset of exif metadata - if you want the rest, you need ExifMeta - option #1.
Note: if you only want to view it, one photo at a time, I recommend using Jeffrey Friedl's metadata viewer instead - he did a very nice job of presenting it (tabular, color-coded, ..).
For plugin-specific support, please contact me outside the forum - thanks.