Passing variable values in Pan shell command

Hello everyone,

I'm trying to run a ".ktr" file through a shell command, that is working just fine, the thing is this transformation uses a variable and I couldn't find a way to pass this variable information. Searching around I found that I could use it as a parameter and it would then work with the "/Param" modifier:

"C:\Users\visagio\Documents\Visagio\Kettle 4.2\Pan.bat" /file:"C:\Users\visagio\Desktop\Projeto Statoil\TO - 00 - Aging.ktr" /param:AF_DATA_EXEC=2014-06-09

The issue is I'd rather maintain it as a variable instead of a parameter, since all my transformations uses variables, and I want to stick to my standard.

Does anyone can give me a hint to how I pass that info to Pan as a variable?

Thanks in advance!