Great Hack!
[high]* akanevsky clicks install
[/high]
Few suggestions though:
- Why not make an additional textarea field in every ushop action, where a user could write custom variables in a form of:
variable:value
and make them evaluate to $vboptions[variable]=value only when running that specific action?

- Hack functions have a messy code which is hard to read. Plus those functions have a lot of variables to be passed. Why not clean it up a bit and comment function variables like Jelsoft does?

- Some sanity when submitting the form, maybe?