This is done by the default IIS Wizard.

Hit Next

Type some meaningful description and hit Next

If you run multiple hosts on the same machine, don't forget to type in the host header name
And hit Next

Type pathname to the root of the website (where ../Web.config and ../bin/SvnProxy are)
This is NOT the path to the repository, the SVN repository is configured in http.conf of Apache
Hit Next

Leave the defaults, Next

Hit Finish

Setting the wildcard ISAPI, go to tab Home Directory, and hit Configuration
On the Application Configuration screen screen hit Add

Copy and paste (or find) your current aspnet_isapi.dll path into field Executable.
Type in .* (dot star) in the Extension field.
Select, All Verbs
Uncheck "Check that file exists" and hit OK

Scrolling down, it should list the wildcard extension. Hit Apply and OK
Thats it!!
Some remarks on running multiple .NET frameworks on you machine.

On the properties screen, goto ASP.NET and verify you got the 2.0 ASP.NET version.
Just some screenshots on the svnroot directory (nothing much to see, really)

Don't forget to configure parameters in the web.config file. It should reference your Apache server.

Start your web server.
That's all.