outbound traffic for specific url by using specific IP

If you have a wildcard forwarding Virtual Server (that is, listening on 0.0.0.0:0), you may also create a wildcard port 80 VS (that is, listening on 0.0.0.0:80), the add the http profile and the following iRule:

when HTTP_REQUEST {
    if { [string tolower [HTTP::host]] equals "www.yahoo.com" } {
        snat 5.6.7.8
    }
}

Change 5.6.7.8 to the appropriate IP (or use a SNAT pool and the snatpool command. Assign your default SNAT (either AutoMap or the appropriate SNAT pool) from your wildcard forwarding VS to the new port 80 VS. That way, SNAT IP1 will be used for all traffic except that bound for www.yahoo.com. Make sure that both Virtual Servers are bound to only the VLAN from which your pool member traffic originates.

If you want to intercept SSL traffic, that is much trickier, because you would need to stand up an SSL forward proxy and the pool members would need to be provided a trusted internal signing certificate which signs for www.yahoo.com. It absolutely can be done, but is, as Mohamed says, not simple.