Path to activity streem with updates only

Hi. I am working ajax for different reasons, and have paths activity streams going something like :
- All activity : mysite.com/activity_slug
- group activity mysite.com/activity_slug/group_slug

And I can't seem to find a way to show only status updates.

I can create a php file with a custom loop and filter the query with "&object=status" but I can't seem to find how to tell my theme to use that file.
activity/index.php is used for all activity
activity/index-groups.php is used for group activity, with a custom loop inside.

any ideas ?