Open a local package as a yum package object w/o all the rest of the yum stuff:
{{{
#!python

# This works in all versions of yum:

import yum.packages
import rpmUtils.transaction
ts = rpmUtils.transaction.initReadOnlyTransaction()
lp = yum.packages.YumLocalPackage(ts, '/home/skvidal/yum-3.2.8-1.noarch.rpm')

# In newer version though you can just do:

import yum.packages
lp = yum.packages.YumLocalPackage(filename='/home/skvidal/yum-3.2.8-1.noarch.rpm')
}}}

replace '/home/skvidal/yum-3.2.8-1.noarch.rpm' with the full path to the package