Just got back from my yearly physical with my GP, who is a triathlete so very understanding about athletic issues. I too have a sebaceous cyst (aka big honking saddle sore that won't ever go away). She said that the only way it will go away is to have it excised, which she recommended I have a dermatologist do (not a plastic surgeon). Fun fun.... 
I will probably wait until the off season since it would take several off-bike weeks to heal, and I'm not willing to give up fall riding, so maybe in early January would be the time to have it done if it's still there. In the meantime, going back to a wider saddle (Terry Butterfly) has helped relieve some of the pressure on it since it distributes my weight over a larger area. I still have a harder, narrower saddle on my mtb, though, and the cyst is a bit tender/irritated now after a longish mtb ride on Wed. night
I feel your pain! 
Emily
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow