The code is based on work by Gustavo, he used webpy

import mapscript
import os

def wxs():    
    path_map = os.path.join(request.folder, 'private', 'test2.map')    
    if not request.vars:
        return ''
    req = mapscript.OWSRequest()
    for v in request.vars:
        req.setParameter(v, request.vars[v])

    map = mapscript.mapObj(path_map)
    mapscript.msIO_installStdoutToBuffer()
    map.OWSDispatch(req)

    content_type = mapscript.msIO_stripStdoutBufferContentType()
    content = mapscript.msIO_getStdoutBufferBytes()  
    response.header = "Content-Type","%s; charset=utf-8"%content_type
    return content

This service can be consumed by QGis (or another client WMS or WFS)

In QGIS url parameter is set to: http://localhost:8000/mapas/default/wxs/

More information