Vanos Seals

Hi all, I have a question concerning the vanos seals. Last summer I changed my valve cover gasket but not the vanos ( that's because I knew nothing of the vanos then ). After some researching I am now kicking myself for not changing the vanos seals at the same time. Any ways long story short I have all seals needed coming in the mail even a seal for the Disa valve too, Since I'm in there why not right? Anyways my question is this 1) do I have to change the valve cover gasket again? I've only put about 17K since last year. 2) Logically I have to drain all the oil out right? & 3) Is there a good DIY video out there that shows the whole procedure from beginning to end? All DIY's that I have found are all people who alrady removed the vanos & just seal are being shown how to change. Since this is my first time would like to get it right once. I'm not scared get in there with or without the video but a little help wouldn't hurt yes!