Update: Sorry I didn't realize this is for your own extra domain. Personal script install support does not come with members with extra domain. What's in it for me.
Here's a summary how to install it:
You uninstalled it.
Now you can't install again.
This is a SEO4SMF issue which I had and can't remember how fixed, but solution is here:
http://www.webmasterstalks.com/When you install it, you'll see a .htaccess (or htaccess.txt) file in /fun (your forum folder).
Edit it and replace RewriteBase with this:
RewriteBase /fun
That's all you need to do.
Then go to admin forum and click on SEO4SMF (it'll show when installed) and enable SEO4SMF.