In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Herzog wrote:

It occured to me that almost all of the problems around the oscillator can be eliminated with a few design parameters.

1. use SMS components for the OSC, even if you have to hand solder them.  After all, the most are two capacitors and one resistor.

2. eliminate putting a 4 pin SX-Key/Blitz interface on the actual board as and addition added feature.  Build an adapter/converter.  You can unplug the 3-pin resonator and used the socket to get 3 of your 4 required leads to a small adapter board for the SX-Key.  Since it is temporary, the V+ could be a flexible wire that jumps to a pin in any convienent location.  When you remove it, the long leads go with it.

3. use the 3 pin resonators with built-in capacitors to further avoid parasitic inductance problems.

In this way, you still have the ability to program in place, but you will only have additional EMI from the programing interface when you are actually using the adapter.

I hope you can visualize what I am talking about.

That leaves the I/O and the Power supply lines.  Much of the talk above and in the excellent prior posting address those problems.
But, it seems that I/O should not be as bad because it is genrally not clocking as fast as the OSC.

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