After a while testing and using the plugin, I found it was actually easier to just use awscli - works great on both linux and windows command lines, and we use it with all our other applications too. More performant in syncing than most of the other language APIs, I think.
In any case, the module that generates the URL is in "AMZ_S3_AUTH_Create HTTP Handle" and it's password protected. Its called from LL_PUT Object Core.vi and you could try rewiring the url going to the generic HTTP PUT vi and/or creating your own vi to replace AMZ_S3_AUTH_Create HTTP Handle.
But just use AWSCLI - you'll probably never look back - it can do almost anything in the AWS system too.