How to programmatically insert sections into RTF document?

Question

I have an RTF document that is generated by Calibre, and as a post-processing step, I'd like to run my custom tool, preferrably written in C#, that would scan the RTF document for pairs of SectionStart and _SectionEnd_tags (any custom string I come up with) that I add to the source document, and turn text between those pairs of tags into sections with 2 columns (equivalent to manually selecting that text in OpenOffice writer, and doing Insert->Section, and in Columns tab - specifying two columns). Is there an example of doing something similar in code? I looked at this article/library, but it is not immediately obvious if it supports it, or if this is even feasible.