Several good answers here, but it seems they try to answer different questions. It is not entirely clear what the real problem is:
1: Michael Urman refers to a bug that can occur with Installshield setups whereby an Installscript custom action runs with interactive user rather than launching user and this can trigger permission problems. If you are using a new version of Installshield this should not be the issue. There are some older knowledge database articles for this: Q108324, Q108340
2: A setup that requires admin access to the computer can not be run as a standard user unless you enforce what is referred to as "elevated rights". In effect temporary write access to most of the system for the MSI whilst installing, but not genuine admin rights.
I am guessing that the issue you are really facing is the latter. In a larger company, elevated rights are generally enforced via its software distribution system. For example Microsoft's SCCM or SMS as it used to be called. There is, however, a more rudimentary way to get a setup to launch elevated, and the method is explained here: http://support.microsoft.com/kb/259459/EN-US - as indicated by Avik.
I didn't find a proper link for changing the DCOM settings, but here is one for a different product: http://msdn.microsoft.com/en-us/library/windows/desktop/ms630816(v=vs.85).aspx. The process is similar.