how to replace the address of the True-Client-ip header to x-forwarded-for header？

e.g.

 configuration

[root@ve11a:Active:In Sync] config  tmsh list ltm rule qux
ltm rule qux {
    when HTTP_REQUEST {
  HTTP::header remove "X-Forwarded-For"
  HTTP::header insert "X-Forwarded-For" [HTTP::header "True-Client-IP"]
  HTTP::header remove "True-Client-IP"
}
}

 test 1

[root@ve11a:Active:In Sync] config  ssldump -Aed -nni 0.0 port 80
New TCP connection 1: 172.28.24.1(39911) <-> 172.28.24.10(80)
1433154499.9974 (0.0196)  C>S
---------------------------------------------------------------
HEAD / 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: 172.28.24.10
Accept: */*
True-Client-IP: 1.1.1.1

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

New TCP connection 2: 200.200.200.14(39911) <-> 200.200.200.101(80)
1433154500.0255 (0.0263)  C>S
---------------------------------------------------------------
HEAD / 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: 172.28.24.10
Accept: */*
X-Forwarded-For: 1.1.1.1

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

 test 2

[root@ve11a:Active:In Sync] config  ssldump -Aed -nni 0.0 port 80
New TCP connection 1: 172.28.24.1(39912) <-> 172.28.24.10(80)
1433154537.6090 (0.0015)  C>S
---------------------------------------------------------------
HEAD / 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: 172.28.24.10
Accept: */*
True-Client-IP: 1.1.1.1
X-Forwarded-For: 2.2.2.2,3.3.3.3

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

New TCP connection 2: 200.200.200.14(39912) <-> 200.200.200.101(80)
1433154537.6109 (0.0016)  C>S
---------------------------------------------------------------
HEAD / 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: 172.28.24.10
Accept: */*
X-Forwarded-For: 1.1.1.1

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

 test 3

[root@ve11a:Active:In Sync] config  ssldump -Aed -nni 0.0 port 80
New TCP connection 1: 172.28.24.1(39913) <-> 172.28.24.10(80)
1433154588.4812 (0.0024)  C>S
---------------------------------------------------------------
HEAD / 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: 172.28.24.10
Accept: */*

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

New TCP connection 2: 200.200.200.14(39913) <-> 200.200.200.101(80)
1433154588.4830 (0.0016)  C>S
---------------------------------------------------------------
HEAD / 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: 172.28.24.10
Accept: */*
X-Forwarded-For:

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