AKAMAI True-Client-IP

How would I do that?

e.g.

[root@ve11a:Active:Changes Pending] config  tmsh list ltm virtual bar
ltm virtual bar {
    destination 172.28.20.111:80
    ip-protocol tcp
    mask 255.255.255.255
    pool foo
    profiles {
        tcp { }
    }
    rules {
        myrule
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    vs-index 28
}
[root@ve11a:Active:Changes Pending] config  tmsh list ltm pool foo
ltm pool foo {
    members {
        200.200.200.101:80 {
            address 200.200.200.101
        }
    }
}
[root@ve11a:Active:Changes Pending] config  tmsh list ltm rule myrule
ltm rule myrule {
    when CLIENT_ACCEPTED {
  TCP::collect
}
when CLIENT_DATA {
  if { [TCP::payload] starts_with "GET" } {
    set snat_cmd "snat [findstr [TCP::payload] "True-Client-IP" 16 \r\n]"
    eval $snat_cmd
  }
  TCP::release
  TCP::collect
}
}

 packet trace i.e. source 172.28.20.17 is translated to 1.1.1.1 when sending to pool member/server 200.200.200.101

[root@ve11a:Active:Changes Pending] config  ssldump -Aed -nni 0.0 port 80
New TCP connection 1: 172.28.20.17(34623) <-> 172.28.20.111(80)
1377937424.0187 (0.0010)  C>S
---------------------------------------------------------------
GET / HTTP/1.1
User-Agent: curl/7.15.5 (i686-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8b zlib/1.2.3 libidn/0.6.5
Host: 172.28.20.111
Accept: */*
True-Client-IP: 1.1.1.1

---------------------------------------------------------------

New TCP connection 2: 1.1.1.1(34623) <-> 200.200.200.101(80)
1377937424.0216 (0.0028)  C>S
---------------------------------------------------------------
GET / HTTP/1.1
User-Agent: curl/7.15.5 (i686-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8b zlib/1.2.3 libidn/0.6.5
Host: 172.28.20.111
Accept: */*
True-Client-IP: 1.1.1.1

---------------------------------------------------------------

anyway, i think using http profile is easier. alternative solution is what kevin suggested.