LyX ⇒ Possessive Citations

[Gnosos]

Using natbib, LyX currently allows citations like "Knuth (1982) wrote TeX." But it does not allow possessive citations like "Using Knuth's (1982) TeX system, ...."

But this page describes how to make a new command, \posscite, that implements possessive citations in LaTeX. By including the code in the LaTeX Preamble, one can use this command in LyX. But this takes you only so far because the command is not part of LyX's interface and therefore requires ERT for every possessive citation.

A better solution would integrate \posscite into LyX's Citation dialogue (Insert > Citation > Citation style). On another list someone suggested modifying natbib.module. I tracked it down and took a look at it, but it's not documented, and I'd have to guess at what to do. Besides, I'm not even sure this is how to modify the Citation style menu.

Could someone please give some guidance here? Thanks.

P.S. I'm actually using BibLaTeX with the Chicago author-date style. I don't think this will make much difference for altering the menu, since the document's bibliography settings are identical to settings for natbib, except that biber is the bibliography formatting engine.