The Table of Contents in my LyX document is multiple pages long, but LyX splits it at an undesirable position. I want to split the Table of Contents manually. An equivalent to
\newpage but only inside ToC. Is this possible?
You could add the following to your LaTeX preamble:
and then add an ERT containing
in your document wherever you wish to insert a page break -
\clearpage - in your ToC.
The motivation behind this approach is that you have no clear handle on the ToC other than by feeding it instructions throughout your document. That is, the entire ToC is created (in general), using a single macro.