A Sydney teenager who allegedly helped orchestrate last year's fatal shooting attack at Parramatta Police Headquarters has been formally refused bail.

Raban Alou is accused of handing a gun to Farhad Jabar, 15, in the Parramatta Mosque on October 2 last year.

Jabar went on to kill police employee Curtis Cheng, shooting him once in the back of the head as he left police headquarters.

Alou, 18, from Wentworthville in Sydney's west, was charged almost two weeks after the incident with committing a terrorist act by aiding, abetting, counselling or procuring Jabar to kill the police accountant.

Over a seven-hour period on the day of Mr Cheng's death, Alou is alleged to have sourced a gun from family friend Talal Alameddine, before he handed it to Jabar and counselled the teenager at the mosque.

Alameddine, 22, is also in custody.

Raban Alou did not apply for bail in Sydney's Central Local Court this morning, and he is expected to appear in Parramatta Local Court in April.

The decision to transfer the matters to another court was made by Magistrate Les Mabbutt, after lawyers for the state argued that Alou's charges should be heard at the same time as his co-accused.

The court rejected a request by Alou's lawyer that a laptop computer be placed in his cell to allow him to access the evidence against him, with Magistrate Mabbutt telling the hearing it was a "matter for Corrective Services".

Lawyers for the Commonwealth also told the court that they needed additional time to allow for the examination of evidence, including CCTV footage and audio from a listening device.