Running .NET 4.5 code from SSIS at NET 4?

I wrote some code that scanned directories for .zip files and unzipped them using ZipFile Class at .NET 4.5. I decided to put it into a job flow in SSIS. When I went to add references for System.IO.Compression and System.IO.Compression.FileSystem they weren't in the list, then I noticed that our version of SSIS was running .NET 4.

Is there a way to run the code with its references to 4.5 some other way than to run it in a Script Task limited to v4? Unfortunately we can't use CLRs or run "commands" from SQL where I work.

Thanks...

Jnana Sivananda