I’d like an icon and label to appear in the section marked in red below, that links to my application canvas page:

Is this possible using any of the current Facebook APIs? No legacy APIs as this is a new app.
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No this is no longer possible; the ability to add Apps to profile tabs was announced as deprecated in August 2010 and removed entirely in November 2010. (ref https://developers.facebook.com/blog/post/415/ )
The bookmarks section (visible in approximately the same place you’ve highlighted, but on the Home / News Feed page rather than the profile) is automatically populated and will have an entry there for your app once users authorise it; this links back to your canvas page or to your bookmark URL if you have one defined