Add a new document with one single page. Provide a placeholder graphic frame on the first page. Set the frame fitting options to your liking. Now select the page in the Pages panel, duplicate the page one time. Next select all the pages, duplicate the two pages one time. Do this until you reach the number of pages you need.
If you already have a document with many pages:
Add a placeholder graphic frame on the first page, with a facing-pages document add another one to the other side of the spine. Set the frame fitting options to your liking. Copy both frames to the clipboard. Go to the next spread and do:
Edit > Paste In Place
Do that with all your spreads if needed.
Have no frame or text selected for the next step:
To place all your images first load them all into the cursor (placegun) with File > Place…
It needs one click per page to place the images throughout your document ( unload the filled cursor above a placeholder frame with one click ) and a bit steering to the next placeholder frame using the scrollwheel of your input device or mouse.
This takes all in all under 5 minutes to place 100 images, I think.