Thank you for posting this. i had asked this awhile back and basically got the response that it was all trial and error. Usually layering sounds will get 'close enough' to the patches you need, keeping in mind that by default you cannot change the volume for the layering without the hack. But I would love to start a list of sounds that people use for certain songs!
I will share that to get the sounds I want, I use the hack that Chandler created and I connect external devices (Macbook and iPad) and software such as SynthOne, FMPlayer2, or a daw like Garage Band/Ableton to get extra tones or custom created tones.
I couldnt find any of the effects onboard made a difference so I use physical guitar effect pedals to really get the delay and reverb particular shimmer for U2 songs.
..and this is how you make your $100 arranger work like a pro rig!