[galaxy-dev] Dynamically Specifying PBS Resources

I'm wondering if its possible to somehow present the user with a param that lets him or her specify number of cores, nodes, memory, and wall time from within the workflow for a specific tool.

Other than coming up with a predictive algorithm for each tool's resource needs (memory especially) how is one supposed to efficiently use Galaxy and PBS other than somehow letting the user specify needed resources? Think in cases like assembly, for example with Velvet depending on the input files, resource requirements can be vastly different job to job.

Thanks,

Ben