is there a place in the .info file to set a url to check for updates?
Yes, you can use project status url:


  Allows module maintainers to define a URL to check for updates to their module using the Update status module. No module released on drupal.org should define this parameter. URL should point to an XML feed that accepts requests in the form of http://my.domain.com/projects/{project}/{core}. In that example, project status url should be set to http://my.domain.com/projects.


See Writing module .info files (Drupal 7.x) for full details.