Getting players to find a bank file and paste the data in the correct spot is a bit much to ask of the user.
The other way would be to let them input the data into an edit box. I've got this up and running and it works very well. While you can input a very large string you can only extract 256 characters which is much too small to allow for any complex data using the "dialog item edit value".
If players are going to be able to transfer info into their map from an external site edit boxes need to be able to access at least twice to four times the current limit.
For curiosity sake what I am doing is inputing a build order from a format which is used by multiple sites which is the one used by YABOT.
For instance if you look here: http://starcrafttools.net/search-builds.php and click on "find builds" there are approx 400 premade build orders which you can get the YABOT encoding for. All you have to do is copy-paste this text into an edit box in my match and it will input the build into the map. Due to the edit box length restriction I am only able to input about 3 quaters of each build :(