You should be able to install it with "opkg install micropython" if you're running trunk or just manually download and install the package. It requires about 250 KB of storage or ~110 KB if you roll your own image.
Note that it's a bare minimum implementation of Python 3.4 and doesn't include the standard library. However there's also a package called micropython-lib that implements a very small subset.
It was added about a week ago and could use some testing. Would also be great to see some OpenWrt-specific applications.
(Last edited by roger_ on 25 Aug 2014, 20:50)