Running Msiexec As Administrator Remotely using PSExec

We moved our product to run on Windows Server 2008.
We run the installation with admin privileged user however since in Windows server 2008 we need to elevate the program although we are administrator.
We do it by opening the comman prompt by right clicking on it and choosing 'Run As Administrator'. Then typing the usual msiexec comman(Msiexec /i "c:\package.msi" /l*v "c:\sc.log").
However when I'm trying to run it remotely using PSexec, it fails on start telling that i don't have the right privileges.
The questions is How do I mimic the manual steps i did into remote using PSexec?
I've tried to Enable the 'Always Run Elevated install…" in Group Policy(Domain and Local). I tried to use RunAs but it asks for password manually which is nit good for me…and I try to run as the actual Administrator User but the installation expext to get the custom user we created…
Any suggestions of any kind will be helpful
Thanks !