Can I use the LATCH system (lower anchor connectors) in booster mode?

Graco allows use of the LATCH system in booster mode only if the vehicle manufacturer also allows it, and the tether MUST also be used if lower anchor connectors are used in booster mode. The maximum child weight when using LATCH in highback booster mode is 100 lb. The child must still be secured with the vehicle lap/shoulder seat belt regardless. (Page 86)