Spinal cord injury (SCI) survivors generally retain residual motor and sensory functions, which provide them with the means to control assistive devices. A body-machine interface (BoMI) establishes a mapping from these residual body movements to control commands for an external device. In this study, we designed a BoMI to smooth the way for operating computers, powered wheelchairs and other assistive technologies after cervical spinal cord injuries. The interface design included a comprehensive training paradigm with a range of diverse functional activities to enhance motor learning and retention. Two groups of SCI survivors and healthy control subjects participated in the study. The results indicate the effectiveness of the developed system as an alternative pathway for individuals with motor disabilities to control assistive devices while engaging in functional motor activity.