I don't think there is any easy way to do what you want. I think you will have to revise the hardware.

I was in a similar situation with a firm that designed a board with a C8051F020 on it and then gave it to me to do firmware. First thing I try to do is configure the peripherals and XBAR and I discover that it's impossible to configure the '020 to match the hardware. The guy who did the hardware got confused by the "Priority Crossbar Decode Table".

I managed to get some of the peripherals working in isolation, by enabling "dummy" features to push some of the pin assignments to the right place, but it was impossible to get everything working at the same time. A hardware mod was required.

You will have extreme difficulty getting /INT0 and /INT1 out to P3.3 and P3.4 without nerfing everything from P0.2 to P3.2

SiLabs has a GUI app that helps you to get the pin assignment and configuration right. I suggest that you use that, then modify the hardware.