Power wheelchair users often use and carry multiple mobile computing devices. Many power wheelchair users have some upper body motor impairment that can make using these devices difficult. We believe that mobile device accessibility could be improved through designs that take into account users' functional abilities and take advantage of available space around the wheelchair itself. In this paper we present findings from multiple design sessions and interviews with 13 power wheelchair users and 30 clinicians, exploring the placement and form factor possibilities for input and output on a power wheelchair. We found that many power wheelchair users could benefit from chairable technology that is designed to work within the workspace of the wheelchair, whether worn on the body or mounted on the wheelchair frame. We present participants' preferences for chairable input and output devices, and identify possible design configurations for wearable and chairable devices.