push to start and stop

Hello my first post but im not new here. I would like some advice on the following. I have a UK spec Iveco Daily When I got it the half the key was snapped in the ignition. for a new ignition set its going to cost hundreds of £. Im too cheap for that. So what I have done is fixed the only imobliser chip that came with the van to the back of the ignition this serves 2 purposes. 1 no remote bypass will work in my vehicle at all for my remote start (Viper). 2 I want a full keyless go system. The ignition barrel is going to be blocked off. I have installed a RFID and using the diagram from this site made a normally open ignition cut off for a momentary switch. The RFID basically sends the signal to the relays mantioned above. All works great (thanks to this site) Now I want to install a push to start button so I can then block off the ignition barrel and have my fully functional keyless go ( ok nearley keyless go the keys need to be in the ashtray ) My question is Can I build a one button set up IE: Push once IGN push twich START push third Engine stop or would it be best to buy a system? I would prefer to press the brake to be able to crank the engine for safety reasons. I did not forget ACC above in my ex Royal mail van it has IGN and STAR the ACC position does nothing. Hope I have not bored you and thanks in advance.

Sorry forgot to mention the vehicle specs Iveco Daily 2.3 Unijet turbo XLWB Right hand drive Ex royal mail 2004