Once upon a time (~8 years ago) I used a signal service which some guy came up with. The arrangement was to use a specific retail broker who placed the orders using Interactive Broker. All subscribers had to sign up for Interactive Broker and sign some form which basically allow the retail broker to control their account. It was certainly cluncky but it worked despite plenty of teething problems. Too bad the strategy didn't produce much return and probably didn't attract enough capital... it kind of just whittled and died after about 7 months. It's not something I'd sign up to again personally, but it doesn't mean yours won't be successful.
I can give you the contact details of the guy who provided the signal service if you are keen.