Maybe there is no appliance because there was no need for one.

Is this the Open Cart you are talking about?

http://www.opencart.com

or this one?

http://www.opencart.org/

I found this information ona website that's providing installation scripts:

The OpenCart project has split into two projects, OpenCart and OpenCartZero. Version 0.93 and below belong to OpenCartZero, and are not compatible with the OpenCart 1.x branch, so no upgrades are available between the two versions.

And as hard as they work they are unable to fulfill all the wishes and desires of the community!

You could always make one! If you make a TKLPatch then there will be one (albeit an 'unofficial' one - but it may become the basis of an official appliance!?)