Python 64-bit in Desktop 10.1

Hello!

I'm having trouble in trying to execute the Python 2.7.2 64-bit inside the Arcmap.
I've already installed the 64-bit background geoprocessing.
When I open the Python command window inside Arcmap and I type sys.version I get the following output:
'2.7.3 (default, Apr 10 2012, 23:31:26) [MSC v.1500 32 bit (Intel)]'
And that is the Python 32-bit version.
How can I run the Python 64-bit version whose path is C:\Python27\ArcGISx6410.1\python.exe, inside ArcMap?????
I need to execute a script inside Arcmap but it only works for Python 64-bit version because it requieres too much memory
and I get a “memory error” in Python 32-bit.

Regards.
Elvis Durán