Do you know where the injury site is? Is it a complete or incomplete spinal cord injury? This will dictate the affected areas and what will be possible.
You have to consider what this individual’s goal are and ultimately if you can help them. Considering they are a paraplegic, you could certainly work on strength and flexibility of the upper body musculature. If they are WC bound and don’t use a power chair, you can work on strengthening potentially weak muscles that oppose the prime movers for wheelchair mobility. This will hopefully lead to a decreased chance of injury.
The ACSM Guidelines for Exercise Testing and Prescription outline some considerations for spinal cord injuries if you have that text available.