Russian Dips without bars

Hey team:

Can you perform these on two plyo boxes? I've tried and it seems possible, but I want to know if it is missing some key element that will keep me from making progress. 

In the proper russian dip form the elbows should be lower that shoulders, so until you can hold this type of standard you can use the support you want.

Thanks Alessandro.

Coach Sommer has stated that using plyo boxes is fine here: 

Thanks, everyone. The double barbell stretched across the supports is what finally did the trick for me.

Christopher, wonderful creativity, please post the video here (if possible).