Perineal muscle training (or pelvic-floor exercises) has been used with some success in men with erectile dysfunction but without SCI.
Courtois et al. (2001; n=10) is worth mentioning since it focuses on the relatively successful use of perineal muscle training exercises to improve penile rigidity in those men with some capacity for voluntary pelvic floor contraction. The approach of maximizing the physiological potential before introducing pharmacological or mechanical intervention is an approach often forgotten in rehabilitation (Elliott, 2003).
There is level 4 evidence (from 1 pre-post study: Courtois et al. 2001) suggesting that perineal training may result in improvement in erectile function in men with SCI who have some voluntary pelvic floor muscle contraction.