Execute Process Task - Arguments as variables

Hello All

I'd like to know how Arguments in a Execute Process task can be represented as variables.  

For example, I have two arguments that are passed to an executable.  Just for some background (but not important to my question), the executable loads data into a complex list.  The first Argument is the Site.  And, the second Argument is an Excel spread sheet with the data.

Like so:

http://devserver/Demo C:\SSIS\Import.xlsx

A space separates each argument.  I want these arguments to be variables but not sure of the syntax or process for this.  I know how to asign a variable to the package but I'm unsure what to do within the Task or if I need more than one task to accomplish this?

Any thoughts?

Thanks