Lucy's blog

Sounds simple enough, but note that you also want your welcome page to show when you click the library. If not visitors are directed to the list. So you must generate some content and set the welcomepage for the wiki list.

       // Create Knowledge List
       SPList knowList = ListCreator.CreateList(currentWeb, "Knowledge", null,
       SPListTemplateType.WebPageLibrary, false, false, false, true, true, false);

       this.generateWikiContent(knowList);

       // Create Procedure List
       SPList procList = ListCreator.CreateList(currentWeb, "Procedures", null,
       SPListTemplateType.WebPageLibrary, false, false, false, true, true, false);

       this.generateWikiContent(procList);

   private void generateWikiContent(SPList wikilist)
        {
            try
            {
                wikilist.ParentWeb.AllowUnsafeUpdates = true;
                SPFolder rootFolder = wikilist.RootFolder;
                SPFile wikiHome = rootFolder.Files.Add(String.Format("{0}/{1}", rootFolder,
                   "Home.aspx"), SPTemplateFileType.WikiPage);
                SPListItem wikiItem = wikiHome.Item;
                wikiItem[SPBuiltInFieldId.WikiField] = wikiHomeText; // string with your html  
                wikiItem.UpdateOverwriteVersion();

                SPFile wikiHow = rootFolder.Files.Add(String.Format("{0}/{1}", rootFolder,
                   "How To Use This Wiki Library.aspx"),
                    SPTemplateFileType.WikiPage);
                SPListItem wikiHowitem = wikiHow.Item;
                wikiHowitem[SPBuiltInFieldId.WikiField] = wikiHowText; // string with your html
                wikiHowitem.UpdateOverwriteVersion();

                wikilist.RootFolder.WelcomePage = "Home.aspx";
                wikilist.RootFolder.Update();
            }
            catch { }
        }