You have to read the error messages from python, try to install the packages on which python depends and then install python.
This might be cumbersome as the dependent packages might again have unfulfilled dependencies and there is no easy way to get a list of all dependencies.
Since you already build the stuff, why not add in local.conf something like this:
IMAGE_INSTALL_append = "python"
and rebuild the image? That way its bitbake which does the dependency resolution for you and installs whatever is needed in the resulting image.
P.S. The Angstrom Project provides binary feeds for a limited number of packages. You might also try to install python from there.
opkg install python