OK, I got this working. Not sure if it's the prettiest of solutions, but "works on my machine"(tm):
```javascript
    var goodLocales = [];
    var yeomanTmp = grunt.config().yeoman.tmp;
    var templateDir = path.join(__dirname, '..', yeomanTmp, 'i18n', 'templates');
    var templateClient = require(path.join(templateDir, 'client.pot.json'));
    var templateServer = require(path.join(templateDir, 'server.pot.json'));
    var totalStrings = Object.keys(templateClient).length + Object.keys(templateServer).length;
```
/cc @vladikoff so he can school us on Grunt config sharing.