Tendons and ligaments have a normal turnover rate of 300-500 days, which is a hell of a long time. They are rich in nerves but poor in blood supply. Tendon/ligament pain is usually due to swelling which greatly increases the turnover rate of these tissues and speeds healing/growth dramatically. The first step is to avoid things that will limit this inflamation (and unfortunatly associated pain) such as ice, anti-inflamatories and especially cortisone injections. Heavy weight, low rep and explosive work will build them but make sure not to overdo it.
I dont advise slow work and here is why, tendons/ligaments structure is one that is designed to hold water which helps absorb immense explosive shock. They are not designed to handle high stress over longer durations.