Supply file name to Command Line Task?

Hello,

I have setup a simple command line task which will call an Expression Encoder program I have created. Is it possible to pass in the file location and file name from my job smil to the my command line task? My task command looks lke this:

"C:\Program Files (x86)\Microsoft Expression\Encoder 4\SDK\Samples\Simple\bin\Release\Simple.exe" <FILENAMEHERE> "C:\Expression\Expression Encoder\JobPresets\sample.xml" "C:\OutputDirectory" -log "c:\logfile"

I need to be able to dynamically supply the filename from my smil as an argument to my program. I have tried {filename}.**, {filename} and a few others but that doesn't seem to work..

Any ideas?