> the following thread might be helpful: Gamecube on PS3

Thanks for the hint but to be honest, that thread isn't helpful. Most of its participants struggled to understand the prospect of both Gekko/Broadway and Cell PPE having basically the same instruction set, rendering emulation superfluous in that regard. The issue of Gekko's/Broadway's different SIMD instruction set compared to Cell SPE's instruction set or Cell PPE's AltiVec/VMX was not even addressed once.
I assume though that the project's author has put more thought into the matter to at least have an idea how to possibly achieve the SIMD mapping. If he decides to map to AltiVec/VMX (as opposed to SPE instructions) the project may come in useful for all hardware platforms based on AltiVec/VMX enabled Power Architecture CPUs, including MorphOS on G4 (and later possibly G5) based machines.