Factory fit bluetooth preparation with rSAP does not connect to Nexus 4 phone

I've a September 2009 Octavia L&K, with the 3 spoke steering wheel and the factory preparation of bluetooth. It has the Bolero radio. My old HD2 phone connected, downloaded the phone book and the car would take control of the phone SIM using rSAP (remote SIM access protocol). It gave me excellent connectivity as it used teh car's aerial.

Now I have a Nexus 4, and in common with many modern phones it does not support rSAP. For some of the other phones there is an app in the play store which enables hardware/firmware that already exists on those phones, but it was not there for any of the pnes I wanted.

Does anyone else have a Nexus 4 phone they've managed to get connected to their skoda or VW group car with the rSAP? If so, how?

I've seen some postings about installing your own system, but to be honest tehy seem to start from a huge amount more understanding than I have. They know their code numbers and can copy output telling what modules are. I'm not afraid to have a go - I've built several PCs over tehyears, but wouldneed more hand holding or step by step.