Create top level domain for multi-site

Hello,

My main domain for my multisite install is word4ya.com

I have succesfully created sub-domains ie; whatever.word4ya.com and they work fine both front and back end.

However, I want to create a top level domain ie; someothersite.com for my multi-site wordpress install.

Is there a tutorial here on the proper methodology to succeed at this on front / back end ?

Thanks.

Jay
CompuMatter