Hi Curly Sue...
I am currently awaiting hand-controls to be installed in my small SUV. I had to complete a 4-hr. training. This consisted of driving their (Rehabilitation's) car which is already equipped with the hand-controls.
I do use a wheelchair at home, but use crutches or a cane when outside of my home, so loading a w/c has not been an issue, although Vocational Rehabilitation discussed fitting my vehicle with a power lift too. I have severe spinal problems and I'm not allowed to lift more than 5 lbs, so I'm guessing that it doesn't require much human strength to operate the lift, or they wouldn't have suggested it. (I would have had to buy a larger SUV or van to accomodate the lift)
Vocational Rehabilitation has guided me through and coordinated the entire process....they've been wonderful. Would your cousin qualify for help through your state Voc. Rehab? Each state has different policies and guildelines, but I believe a common criteria is whether modifications, equipment, etc. will enable you to work or attend school. It might be worth talking to someone from that office and find out what help is available. If nothing else, they may be able to direct you to an agency that can help. Perhaps call a local reputable Physical Therapy Clinic for guidance and/or referral.
I hope I've been a little help here. My situation is different than your cousin's, but I hope you'll be able to find a place that coordinates these services/equipment, based on your counsin's abilities and needs.
Good Luck!
~Teri