If this traffic is not encrypted before it gets to an external firewall, it is possible to capture network traffic either as it leaves the PC or just after it leaves the PC before the firewall.
If the traffic is encrypted by your application, there are proxies that can decrypt/encrypt HTTPS traffic in order to change the source address of the traffic. Whether or not a particular proxy lets you capture the decrypted traffic before it re-encrypts is something you would need to research. Large companies often use these sorts of proxies, and some allow the company to do this in order to snoop on employee web use. These are typically high-end, dedicated proxies that require lots of CPU horsepower.
You will need to do your own research to see if there is a product that fits your needs. Product/resource recommendations are specifically off-topic for this forum.