Update the pyenv page

doc/source/misc/pyenv.rst

 .. _pyenv-install:
 
-Pyenv - Installing python 3.4 as a user
-=======================================
+Installing python 3.4 as a user
+-------------------------------
+
+Pyenv (x86/x86_64 only)
+=======================
 
 Pyenv_ is a useful script that allows you to install several python versions
 in your user directory, and lets you manage which one you want depending on
@@ -19,6 +22,17 @@ Then you only need to add a ``.python-version`` file containing ``3.4.2`` in
 your poezio directory to make the python version in that directory default to
 the python 3.4.2 installed with pyenv.
 
+Building your own python 3
+==========================
+
+- Go to the `python download page`_
+- Select the “Latest Python 3 Release”
+- Download a tarball and extract it
+- Run ``./configure && make`` (takes a few minutes even on old CPUs)
+- Edit the poezio launch.sh script to make it call your user-compiled python
+
+
 .. _Pyenv: https://github.com/yyuu/pyenv
 .. _installation tutorial: https://github.com/yyuu/pyenv#installation
 .. _automated installer: https://github.com/yyuu/pyenv-installer
+.. _python download page: https://www.python.org/downloads/source/