You don’t necessarily need an erection. You just need enough blood in your penis to work with. That can be archeived with kegels, dry jelqing or masturbation. You can also start with porn to get things started, but quit watching it after that. Once you have enough blood, you are not supposed to let much of it out, but push more in, that’s the principle of jelqing. So when you’ve gotten started, you don’t really need an erection to keep jelqing.
"Be aware that there are several schools of thought here as well. Some seem to go with the hard and heavy approach. The sessions are brutal. You can hear them talking to their dick: You better grow mofo or I will punish you even harder tomorrow! Others seem to favor a more tender approach. Always listening to what their member is saying while massaging it gently and singing to it with a soft voice. If it is moody and not happy with new behavior, they always listen and are very understanding."