Thanks for the resources. I tried to use paver but it seems to be a bit painful to implement, for a non-expert developer, no?
Furthermore, by default, pip is not installed even with the OSGeo4W installer. Could you paver script works without it?
To install it, I followed these instructions and I produced a batch file (see below) but doesn't solve the admin rights problems:
@echo off
Title "PyPi in QGIS"
Echo "Adding 3rd party modules in QGIS"
REM securely download get-pip install script
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
REM install pip
python get-pip.py
REM install 3rd party modules
pip install --user arrow
pip install --user requests
pip install --user requests[security]
@echo on
pause