Unfortunately, Hazel doesn't really work in a batch fashion like that. But, you could write a rule to operate on the folder as a whole. In such a case, though, you will have to use your own script to do the actual importing.
I'll have to think about whether Hazel should do batch processing and if so, how it will present that to the user without confusing things.
For now, though, I think an Applescript is the way to go, or use cron. You could have Hazel move files into a folder and a cron job that will take all the files in that folder and import them wholesale.