The former Hearts man has been training with the Glovers in recent weeks and Johnson believes he has the passing ability to boost his squad, currently rock-bottom of the Championship.
And with the visit of Watford on Tuesday night followed by another home game against Doncaster on Saturday Johnson is keeping his eyes peeled for international clearance.
"I'm waiting any minute now for us to get the okay," he told the Western Gazette.
"He's a Spanish footballer and that tells you it all, already. He's comfortable on the ball, he sees a pass and he's a good athlete.
"He played 120 games for Hearts in the Scottish Premier League regularly. He needed to spend a couple of weeks with us to find his fitness and get back into the English way of playing.
"We have got him into it and he's a competitor that can spot a pass and that's really what we need to add to what we've got."