Add Sitemap update to solution

HI guys,

Can anyone advise how to add a custom entity to a specific location in the sitemap in a solution?  I know I can add the whole sitemap to the solution, but I would rather just be able to specify where to add the specific entity to the sitemap.

I assume this can be done by editing the XML in the customisations file, but I am unsure of the syntax required.

Please note, I know how to specify the Area an entity appears in, and I know how to edit the sitemap with the XRMToolbox, but I'd like to be able to do this via a solution, but without having to import the whole sitemap

It's probably worth noting that I'm trying to do this with an unmanaged solution