It was quite a first day on the job last Thursday for Soho parking lot attendant Manuel Roca, at left. When someone stole a Jeep S.U.V. that was waiting at the curb to be put into the parking lot at 81 Mercer St., Roca jumped into his own S.U.V., which was also parked on the street, and gave chase in hot pursuit. Within about six blocks, Roca cut off the stolen vehicle on Broadway on the north side of Canal St. Meanwhile, police had heard a yell for help, broadcast the car theft over their radio and quickly converged on the scene. When the suspect jumped out of the Jeep and took off on foot, a swarm of plainclothes and uniformed police were there to arrest him, in photo at right. The suspect was identified by police as Johmal Enoe, 28.