I looked at the old 1.2 assemblies, and essentially copied the beginScrollView and EndScrollView methods.
Code Select
public override void DoSettingsWindowContents(Rect inRect)
{
Listing_Standard listingStandard = new Listing_Standard();
Widgets.BeginScrollView(inRect, ref scrollPos, scrollRect);
inRect.height = 100000f;
inRect.width -= 20;
scrollRect = new Rect(0f, 0f, inRect.width, listingStandard.CurHeight+100);
//Actual ui stuff here
Widgets.EndScrollView();
listingStandard.End();
base.DoSettingsWindowContents(inRect);
}