The 30-year-old, full name Borja Perez-Penas Diaz-Maurino, will be tasked with filling the boots of creative attacking midfielder Dean Shiels following his move to Rangers.
Borja has spent most of his career in the second and third tiers of Spanish football, latterly with Alicante and Alcorcon, for whom he scored two goals in a 4-0 Copa del Rey victory over Real Madrid in 2009.
Shiels, whose team have scored one goal in two drawn SPL games, said: "Borja Perez has signed until the end of the season. He plays at the top of the midfield, the same as Dean Shiels, so we are trying to get that creativity into the team.
"We need finishers as well but he is one that certainly I am pleased to get. We will probably need a goalscorer to take the pressure off Paul Heffernan and Rory Boulding.
"But Rory Boulding has some education in how he play now so he is hopefully ready to play from the start quite soon."