There are no more L45. All the Learjets have been replaced by Cessna Citation Mustangs.
If you are selected for SIA passenger fleet, you will go through the Mustang course before doing the type rating for 777. SIA is in the process of getting CAAS' approval for the A330 Second Officer training.
If you are selected for SilkAir / SIA Cargo you will proceed straight for type course after the CPL/MECIR test in Perth.