You can use ddms which has option to take screen shot.
On DDMS -> Select Device -> Select Screen Capture
Edit
AFIK its not possible but this scenario will solely depend emulator image. Device hotkey might work on some OS images. Try same key combination from emulator link.
If your emulator uses factory or same images then it should be possible. You can download factory images for your emulator. see available nexus images from this link also it is possible to download images from manufacturer site.
Alternatively you can take screen shot following way,
View content = findViewById(R.id.myView);
content.setDrawingCacheEnabled(true);
Bitmap bitmap = content.getDrawingCache();
And later save this anywhere you like. This is not optimal solution and it will only print what you have inside your view.