No way to do that automatically. You could use a table for everything and that way you could just add or delete a row.
You might also look into one of the automated catalog plugins.
We are using easy catalog for a parts manual. Course we do have text in a database that is used along with the photos. But, you can set up a table and tell it what photo to use. You would have to use a database like Access to identify each photo and then update when needed. It isn't as costly as some and they have great customer support!!
Put your images in-line in a continuous threaded story, separated by a single hard return.
You used to be able to create Indesign Contact sheets in Adobe Bridge. If you're running CS3 it can do what you need, but you'd have to create a new file every time.
Maybe there's another solution to whatever you're looking for as an end result...
If I was doing this in Indesign I think i'd use data-merge and update the document with an updated spreadsheet when ever the new image is added (you could even have text if you needed it at a later date)....but if you only need a contact sheet, Bridge is probably the best place to do that.
As start you maybe can use the build in applescript ImageCatalog.applescript.
You can automaticly import your images with a fixed number of images on a page.
Maybe this ive you less work to build the cataloge.