I was wrong about this. The feature is "hidden" in the Load File box. When you load a file to the buffer a options box comes up and one of the pull downs on the right side of the box let's you load "first byte of two byte word" or "third byte of four byte word".@jessenator I finally loaded the software and started using my TL866II+ and I even read the manual all the way through. Gasp.
Sadly, the Xgecu software does not include a feature to deinterleave a wide .bin file for programming on narrower chips. For example, you have a 32 bit wide ROM file for the Wombat and need it deinterleaved across 4 8-bit wide Flash chips.
You'll need to write some kind of program or script to do that yourself as a separate step.
It shouldn't be difficult, but it is another step.