It is possible to create an MSI file to initiate the install of IE6. The file to launch the IE6 install is ie6setup.exe. You could use the same idea to launch EXEs. (Taken from Wise newsgroups)
Solution #1
You need to get the MSI wrapper from MS directly.
http://support.microsoft.com/default.aspx?scid=kb%3ben-us%3b810011
Joseph White, MCSA
ONE's Technologies
Solution #2
You could use a MSI wrapper script, which could start the installation of IE.
One can be found at www.installsite.org under Windows Installer -> Tools and Tips. It is called "MSI Wrapper to Deploy Internet Explorer with GPO" written by Vincent van Egmond.
I have tried it a few times myself and it seems to work.
Please note that this is NOT in compliance with Microsoft or any well-known practises to package and deploy IE via MSI. Your approach (using IE Admin kit), creating an installation point of IE, is the way to go.
Michael Buchardt
Sometimes you need to keep the installation logic inside the setup.exe intact or you need to automate the installation of a driver. You can do this with an MSI by using a custom action inside a virtually empty MSI package. Microsoft Knowledge Base Article – 260301 covers this for installing SP1 for Windows 2000 via GPOs. When deploying software using GPOs it is best to use MSI Packages as much as possible.