I used this guide, and step 8 says it will do what I want. What is strange is that while the admin user I created is allowed to browse through the entire system and transfer files both ways (like I want), it cannot overwrite any files that already exist on the server (thus it is not a very useful user). It can overwrite files from the server to the computer that is connecting, but it cannot go the other way.
The error I get is
533 Could not create file. Is this a permissions problem somehow?