I know we all like ready made assessments.... but for this activity type I think it's most important to make assessment 'built in'. That is, depending on how you are emphasizing learning/doing elements, give the students clear 'checkpoints', so that they have self-assessed (or worked through with you) before they move on to any next steps.

Each of the first 4 lessons can be assessed that way, while #5 depends on whether you want to assess Presentation skills. Again, if it's worth assessing, then it's worth teaching first!

Having said that, Gene Yang has made a good rubric for helping with student/teacher assessment of the elements.
http://www.humblecomics.com/comicsedu/
or
http://www.geneyang.com/

Lessons Overview

#1 Picture This

#2 Storyboard 2

#3 Lights, Camera, Action

#4 Word and Thought 'Balloons'

#5 Presentation or Publication

Resources

Links to samples

Assessing the Unit

Extensions & Ideas