Innosetup, best practice custom installation pass variables to external application - inno-setup

Question

I've got an installation task using InnoSetup which I'm not quite sure how to do properly.
Situation is as follows:
1 innosetup custom page with some textboxes and checkboxes. Basically containing targeturl, and a windows servicename. Might be more later.
This custom information needs to be passed on to two different app.config files.
Question is now, how to do this?
My first intention was to use the [Run] segment with a bunch of parameters such as:
[Run]
Filename: {app}\MyApp.exe; Parameters: /install; Flags: runminimized
But I don't know how to pass the custom data to the application.
Perhaps one can create some environment variables and pass the data that way?
Perhaps one can create a temporary file with necessary values?
Perhaps one should do this in a loaded dll during the installation and not post install?
Any suggestions would be very much appreciated.

Answer 1

and thankyou. For "#DenverCoder9":
Basically what I ended up doing, which is almost line for line in the bundled examples from Inno-setup. Missed the fact that Inno-setup allows for XML manipuation (via MSXML), which allowed me to to:
include a sample configuration file (app.config.sample).
load the sample configuration file
modify it using the collected data from the custom form.
save it to the correct location.
[Files]
...
Source: ..\UpdateService\UpdateService\Server\bin\Release\UpdateService.exe.config; DestDir: {app}; Permissions: users-modify; Flags: comparetimestamp onlyifdoesntexist; AfterInstall: MyAfterInstall;
[Code]
procedure MyAfterInstall();
var XMLDoc : Variant;
var RootNode : Variant;
begin
// if(FLAG_UPDATE_SERVICE_CONFIG) then begin
XMLDoc := CreateOleObject('MSXML2.DOMDocument');
XMLDoc.async := False;
XMLDoc.resolveExternals := False;
XMLDoc.load(ExpandConstant(CurrentFilename));
RootNode := XMLDoc.documentElement;
...
end;
end;
This has the added benefit that I have a sample file to provide for anyone who needs to modify the application by hand.

Answer 2

Can you not use command-line arguments to pass values entered in your Inno Setup installer to an external application?
The external application (which I assume is .NET) can handle writing the values from the command-line to configuration files (i.e. 'App.config'). The Main(string[] args) method of the .NET application can examine the command-line argument values. Use the [Run] section as you suggested and pass these values as parameters (using Parameters).