C++ 11 backporting to C++2003 [closed]

I have a situation in my project where we use Tasking Compiler v6.3 and develop code in C++11 standard. But we have one more porject which uses different compiler version Tasking V4. unfortunately this version only supports till C++2003. Now our question is without investing lot of time to rewrite our complete code is there any possibility to backport to C++2003 standard? Thq