Hi There Again,
I have a script that will do what you need it to do. It requires a file to be set up similar to how I described in my earlier post to you (the one you verified), and your file as the source. The script will convert your file to my file, fill in the first default Purchases account on the vendor and the cash account assigned to either the credit card or the checkbook assigned to the credit card (in the setup).
The calls to SQL are based on a connection string that assumes the currently logged in GP user has permissions to run select queries on the checkbook, vendor card, credit card, and GL Account tables (see the query for the tables in the script).
You are free to modify, or do what you like with the script, and I would recommend you test the script first to ensure it will be sufficient for your needs before putting into production.
Attached is a zip file with 3 text documents in it. The script document is what you need to paste into the "Before Integration" script for the AP Transaction import. The AMEX.txt file is the source file you would get from the statement. The AMEXIntegration.txt file is the output file that is generated from the source file, and it is what you need to map your AP transaction integration. All of the column names are case sensitive and required on the source file. This is so the VBA script can find values needed to get defaulting account information from GP.
You can add additional columns to the source file as long as you keep it tab separated, and all columns have a header. The destination file will have a "seq" column added as the first column, and distribution columns added to the end. Everything in the middle on the integration file should match your source exactly. Again, you will use the integration file to do your header grouping and distribution mapping to the integration using the "seq" column as the key.
It's pretty straight-forward, and let me know how it works for you or if you have questions. All the VBA code is commented heavily, so you can feel free to modify or play around with it if you need to do something different. It will show you a good way to open, read, write to text files, and how to open and read from GP tables using the connection object in GP. This is nice because you can use SQL permissions instead of hard-coding a user id / password into the connection string.
[Edit]
Also, this script will handle document types of Invoice and Return only. Credit memos will not produce a cash transaction. If you pass any document type other than the specified, they will be ignored in the integration file.