If you get a tunnel open, you would need to have LUM installed on your machine, and designate your machine as a central registry server. Services need to be running to be able to process any license. Then you would need to specify the location of the network license server. (the network location of the license, wherever it resides)
I'm not a LUM expert, so use my advice as a building block - speak with someone who knows, for sure. If you know what reseller your company bought Catia license from, they will be more than happy to help you with this. (unless your company has an authorized contact - then you would need to go through them)
You do also understand, that you can only get the license if nobody else is using it, right?
If you have the ability to get the concurrent offline, that might be the best option, as it could be granted on a schedule.