[TYPO3-english] Two domains

[Sergio]

I've got two domains on the same page:

1) http://www.domain1.com
2) http://www.domain2.com

I would like that when I'm in a certain branch of my page tree, pages
would use one domain, and if I'm out of that branch, use the other one. 

Something like that:

[PIDinRootline = 1]
 	"use_domain1"
[else]
 	"use_domain2"
[end]

Would you know the sentence on TS to "use one domain"?

Thanks in advance, 
Sergio