I very much doubt you would be able to place files on another server without HUGELY compromising the security of that server (you would essentially be allowing anyone to place file there!)
I guess you could put an SC file in a project (or other implementation of an API) on the subdomain and call it using an API step of your Server Connect (probably with some kind of token/passcode to stop any old tom/dick/harry from uploading files to it, malicious or not)