Imbed the php-fusion into its own directory

I'm wanting to imbed the php-fusion into its own directory, allowing me to have it in something like www.website.com/portal/ or portal.mywebsite.com

To achieve this I know what to do, I just want to make the files where there not accesible such as my hosting company doesnt have direct sub doamins I have to link directories to the domains for the data to be pulled from.

So if you were to visit portal.mywebsite.com you could access the poral but you could also access it from www.mywebsite.com/portal (or however and where ever the directorie lies), I want to make it where its only accessible from the sub domain, and hot from a general directory level.

Any ideasm sorry if this is confusing, dont knwo how else to explain it.

thanks

the nerd