How to make Sublime Text 2 spell check comments only?

The built-in spell check feature seems to be running over the whole code, underlining lots of text that is supposed to be that way i.e. the code itself.

Any way to limit it to just comments (//)?

There is no direct way of limiting the spell checking parser to only comments in Sublime Text 2 (but this is simple to do in Sublime Text 3). These programs are not written to differentiate text document and some code syntax. So most of the code syntax looks like spelling errors. The best solution is to toggle spell-check with F6 and right-click on the spelling error to change the spelling. Or use Ctrl+F6 to move to next misspelling and change it.