mine has tether hooks installed (not sure if they were dealer installed or otherwise). annother resource if you are not sure if you are installing the seat correctly would be your local firehall. i know that we as a policy will help and advise people at our stations (full time stations) not sure if your area may be volunteers if you are in a rural area. st. johns ambulance and police stations may also be able to assist.
Both of my child seats have a tether in the back that attaches to a small bracket on the back of the bench seat and then two mini seat belt contraptions that plug onto and grasp small metal bars back in the corner of the seat. You kind of have to dig for them though, they are set back in the crevice of the seat next to where the regular seat belt connectors are.
Follow the directions that came with the seat or if your unsure do what others have suggested and run by the local fire department. This is one of those things you dont take a chance on. We have 5 kids 8 and under and all the various seats we use all mount very securely in the rover, just take the time to follow the directions.