Good news is now I am still using ld, like what is generated in the Makefile file by configure script, and able to do the linking process for the built-in modules successfully. 

I only need to set CC="cc +DD64" and "CXX=aCC" and the process make process is able to build python executable 64-bit and all the built-in modules where the necessary bit can be found.

For other built-in modules, for example, _tkinter, I am also able to build it this time by setting these 3 environment variables where ~/local is where I installed my tcl/tk binary.

export CC="cc +DD64 -I/home/r32813/local/include"
export CXX=aCC
export LDFLAGS="-L/home/r32813/local/lib -lxnet"

I am finally able to build python 64-bit and built-in library on HP ia64 using HP compiler aCC. Thanks for the input everyone. :)