Without Group Policy you will need PSExec from sysinternals:
The real solution is to have the remote machine run msiexec.exe and then point to the MSI package as an argument of the msiexec. You need the MSI package placed somewhere on the network accessable by the remote machine with the credentials that you supply to PSExec.
Customize and run this command to your needs:
psexec \Server -u "DOMAIN\Username" -p "PASSWORD" cmd /c "msiexec.exe /i "\Server\FolderShare\My Install.msi" /quiet /norestart"
NOTE
- If your MSI or server path contains spaces then surround with quotes
- Run psexec with the @filename to install on all the listed computers. In a seperate file create a list of computers to run against, one computer per line, and do not include the leading '\'. ie. (blank lines unneccessary but the stupid forum keeps putting them in there)