Sage Paperless Construction may be able to aid in that process.

na.sage.com/.../Sage-Paperless-Construction-Sheet

How many jobs on average per PM?  

Why not attach the invoices to the data entry, and flag the invoice with the hot list check box and put the status as review.  

Then the PM's can open up the job through the Project Work Center and see the flagged invoices for approval.  They drill down on each one, review it, change the status to approved.  You can also use the note pad on the invoice to communicate with each other.