The veteran midfielder joined on trial earlier this summer but is yet to officially join the club.
The Gers boss was speaking to Rangers TV ahead of this weekend’s clash with Falkirk when he was pressed on the current situation facing the former Derby man.
“He’s just trying to get fit and once he is we’ll sit down and have a conversation but he’s gotta get fit and he’s in the process of doing that,” said Warburton.
The 35-year old initially arrived in July on trial with the intention of proving his fitness before being awarded a deal, but three months on and he is still officially without a club.
When asked whether Eustace was ‘on the books’ at Rangers Warburton replied: “Not at the moment but he’s got a role to play here right now so he’s working with us and his experience is vitally important.”
Eustace has continued training with Rangers and is believed to be mentoring a number of young talents at the club, with Ryan Hardie one such player to come out in praise of the veteran - in a Twitter Q&A session.
Whether he will be able to prove his fitness and take to the field for Rangers is still up for debate but Warburton insists he was brought in with a view to making a contribution on the pitch.
“John’s a good guy. He’s played at the highest level for a number of years, outstanding player with a great knowledge of the game,” he added.
“He’s going to be an excellent coach in the future but right now we want him to be player for Rangers.”
As far as a potential timeline for Eustace’s introduction, Warburton was non-committal but suggested it’s not too far away.
“Hopefully we’re talking a couple of weeks," he said.