Help change oil please?

My daughters boy friend who knows nothing about cars or bikes, just bought a 1998 1200 Sportster, i am a auto mechanic and have had lots of Japenese bikes. He wants me to change the oils in his now and i know very little about Harleys so before i attempt it, i would love to have a basic howto on changing the oils.
All i do know is its a dry sump, its filled via the tank, i dont know how to drain it, nor how to, or where to fill/drain transmission.
He has bought Harley 20-50 oil to put in it.
Upon reading some web sites, i see a Harley Sportster should have a different tranny oil than other models? this correct?
And yes i know we ned a reapir manual, thast coming but bike has sat since last summer and he is aching to ride it , so am i thanks

thanks hotroadking

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