bat file to execute ssis package with run as specific user

so i am banging my head against the freaking wall over here and cant seem to get anywhere so i have decided to try a new method of executing a ssis package...

I have not been able to run this SSIS package in a job even after creating a proxy acct. but it will run if executed in SSIS.

http://social.msdn.microsoft.com/Forums/en-US/sqlintegrationservices/thread/9eff7fbc-0af0-4f52-9f92-8c12c556dc50/

So I am wondering if i can create a bat file to run the package as a specific user.