I use two-sided document mode in Book class KOMA Script. It works well in the sense that the ToC, chapters, titles starts from the odd pages. Exactly we I need in a book.
In a recent book I need to have asymmetrical text blocks in one spread—aligned to the left—in order to accommodate the margin notes to the right, and yet I want the beginning of the book (intro, ToC etc.) and the colophon to have a symmetrical layout.
Since the two-sided mode defines the margins as inside---outside, which is a symmetrical layout through the spine, how can I have an asymmetrical margins in the two-sided mode?
The second question is, how can I turn back to symmetrical margins for some particular pages?

