I haven't found anything that works. Vacuum erection sort of works but it is not very comfortable. Good luck.
Hi,
Post prostatectomy erectile dysfunction can be treated with a group of drugs known as phophodiesterase type 5 inhibitors, another treatment is transurethral alprostadil, and sometimes vaccum erection has to be used.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1477601
I would suggest you to discuss these options with your treating doctor.