Steve Guinan is not currently on the Cheltenham squad list as published on their website.
Usually when a player goes out on loan reference is made to that loan on the websites. For example Keith Lowe is on loan at Cheltenham from Wolves and he is on the Cheltenham list.
Guinan's loan at Hereford finishes shortly and an announcement about his future has to come in the next few days.
His first game for Hereford was against Notts County on January 27th so he can not play for the Bulls after Saturday's game against Rochdale unless or until an extension to the initial loan has been agreed.