I converted the FedEX labels piece a while back, I don't use the base OSC version so my conversion is not going to work for the mass. I really have no interest in setting up a test environment and re-coding it. I hard-coded most of the values I used and didn't drive it off a module.
Here are some pointers.
1) When you code against FedEX labels it needs to be done with a test account, Production accounts won't work until it's approved by FedEX.
2) You have to go through a Label Certification Program and send FedEX each type of label you use. When I did it I just did I just did these Labels.
$service_type = array();
$service_type = array('id' => 'GROUND_HOME_DELIVERY', 'text' => 'FedEx Home Delivery');
$service_type = array('id' => 'FEDEX_GROUND', 'text' => 'FedEx Ground Service');
$service_type = array('id' => 'PRIORITY_OVERNIGHT', 'text' => 'FedEx Priority Overnight');
$service_type = array('id' => 'FEDEX_2_DAY', 'text' => 'FedEx 2day');
$service_type = array('id' => 'STANDARD_OVERNIGHT', 'text' => 'FedEx Standard Overnight');
$service_type = array('id' => 'FEDEX_EXPRESS_SAVER', 'text' => 'FedEx Express Saver');
3) MPS (Multi-Piece Shipments) labels, is not intuitive, that's the tricky part to code. (It wouldn't be so bad, but FedEX documentation is lacking in some area's).
4) When you get certified, you have to do a MPS Label and a normal Label for each method you use. So when I got certified it was for 12 labels (6 normal labels and the 6 MPS Labels to go with it). But I also heard of FedEX just approving accounts for the advance services, I wasn't lucky.
5) You need to use the "Ship Service Web Service" and the "Track Service Web Service", I guess the track service isn't really needed, but I did that piece of it too.
If anyone attempts a module, I can help you get past the tricky parts, but I have no interest in doing it. Once was enough.
I'm attaching the tracking piece, it *might* plug in directly. But the other pieces wont.