I'm able to define a custom toolbar for a ckeditor control in asp.net using just the ToolbarBasic property within the page markup. I do it like this:
<CKEditor:CKEditorControl ID="CKEditor1" BasePath="/ckeditor/" runat="server" Width="100%" Toolbar="Basic"
ToolbarBasic="|Bold|Italic|Underline|Strike|-|NumberedList|BulletedList|Outdent|Indent|-|JustifyLeft|JustifyCenter|JustifyRight|JustifyBlock|-|Link|Unlink|-|TextColor|-|Undo|Redo|Cut|Copy|Paste|PasteText|PasteFromWord|-|Find|Replace|SelectAll|-|Image|Table|HorizontalRule|SpecialChar|-|Format|" ></CKEditor:CKEditorControl>
This creates a custom toolbar with all of the specified items within the same "section" i.e. they are sort of grouped together. Where a |-| is specified, this creates a small vertical line between the items but the items remain in the same "section". I can see that when using the standard "Full" toolbar, the items are split into multiple sections but I'm not sure how to do that using the above syntax.
Unfortunately I don't remember where I originally found this syntax online and have taken it from an old project of mine. Now I cant find any information about this syntax online and all searches give information about defining a custom toolbar in different ways.
The version of ckeditor I'm using is 3.6.6.1.