Question regarding spoofing

There exists programs such as synner.pl or Xxpoof where one can send spoofed source packets to a target IP address. However, this is only limited to IP addresses. Is there any such way to do the same thing, but to a certain URL, rather than IP?

Say, for example, that example1.com and example2.com share the same IP address, but you only want to spoof an IP packet for example1.com, not example2.com. Would this be at all feasible?

With that in mind, would I need to develop a separate HTTP packet using an HTTP Perl package? I can develop a spoofed packet with Net::RawIP, but sending HTTP headers is another story. I was thinking of using the HTTP::Headers module to send HTTP headers following the IP packet if that's a possibility, hence I was asking about the "data" header.