Web deployment project - Launch conditions .NET Framework

I've created a deployment project for a small web application I've been developing.
Everything is working fine, but I want to change the InstallURL in the launch conditions for .NET Framework if the user do not have the required .NET version.
So that they do not have to download and run the update file.
Instead I've downloaded the file and want it to run automatically if needed.


Let's say I have a MyWeb.msi and dotNetFx35setup.exe file.
I then just zip them together and send the files the the user. The user extracts the files and run the .msi file, lets say at C:\MyDocs\MyProgram\.
So my question is related to the InstallURL property.
I've read that the InstallURL could refer to folders, but usually on CD's and they have static folder paths.
In my case the path may vary from each user. So how do I set the path to where the files have been extracted?
I've tried just to enter the filename dotNetFx35setup.exe in the InstallUrl since I thought the default path would be where the file was extracted, but this did not work.

This is my first time creating a deployment project, so there might be several other ways to run the file if need. So all solutions are appreciated.

Regards
Marius