For those who are unfamiliar, to "mirror" a web game means to make it available via your own web server. If you just want to play the game offline by yourself, you can download the old MS-DOS versions from the Yahoo Group. You can download either the male version or the female version separately.
To mirror Alter Ego, you'll need your own dedicated web server. Ideally this would be a machine you control completely, because Alter Ego can use a lot of system resources.
Alter Ego requires that you install a Java web application server, such as Tomcat. If you only have "web space", i.e. disk space for serving up simple static web pages, you won't be able to mirror the game.
As for "other requirements":
If you can satisfy those requirements, setting up AE is (or should be) relatively simple.
I'm afraid that I have precious little free time these days, so I may not be able to help you set this up if you get confused. Furthermore, these directions may be incomplete or inadequate... I've never tested them myself. If you didn't understand these directions at all, I'd probably recommend against trying to set up a mirror. But if you have a small question, feel free to address it to me and I'll see if I can get around to helping.
Good luck!
Dan Fabulich
dfabulich at warpmail dot net