The 30-year-old, who has been training with Pompey for a number of weeks, will remain at Fratton Park until the end of the current campaign.
When he returns from his loan spell, Boco will once again link up with Portsmouth boss Paul Cook after working with him at Sligo, Accrington and Chesterfield.
Transfers
Exclusive: Spurs line up move for 'Austria's Peter Crouch', Jose safe for now
22 MINUTES AGO
Champions League
Real Madrid's Ramos tests positive for Covid-19
35 MINUTES AGO
Football
Tuchel wants 'instant success' at Chelsea
AN HOUR AGO