Yes, it is possible. I connect to my customer's Sidewinder's all the time.
You will need to ensure that wherever you are located you are able to make an outbound connection to the Internet on TCP port 9003 - this is the port number used by the Admin Console service.
On the target Firewall you need to have an externally-facing Admin Console rule. Even though it uses a bespoke GUI and the connection itself is encrypted by the Firewall certificate, you would be wise to make sure that the rule is locked-down to stop anybody from connecting.
The easiest way I can see of doing this is to create a network object for your trusted external IP address (if you have more the one location then create multiple objects and place them into a netgroup). Then duplicate the existing Admin Console rule (which allows access from the internal side) and change the burb values and source endpoint to something like this:-
With this rule in place you will be able to configure an entry in your Admin Console GUI to connect to the Firewall's external IP address, and that's it!