A center installation in a Toyota is generally not allowed using the
LATCH system. The excerpt for the Quick Ref guide from the
LATCH manual is
here.
You can use center seat belt to attach your
SafeSeat to the car. I would also make sure to follow the child seat manual's instructions for a seat belt installation and that the child seat does not touch the driver and passenger seats (~1-2 inch clearance space).
Hope that helps!