There is an ebuild for dev-python/pip in Gentoo Bugzilla Bug Report No. 317791
. You can click on the link Bugs
at the top of this page, to file a request for the package to be built and included in the Entropy repository. Alternatively you can install the package via Portage using a local overlay. If you don't know how to use a local overlay, see the post Re: epson tx300f can't print
for an example.