You can use john guest fittings (quick connects for ro tubing). Get a half inch push fitting and run a drill bit through it (to remove the tube stop). That fits over the maxijet. Thread that john guest fitting into a 1/2" thread thread adapter. On the other side thread a john guest 1/4 fitting and you should be able to connect the 1/4" john guest to the maxijet.
Hope this helps.