Was testing aldos BdEmuPartitionTool for him and responding to problems with ps3gen writing .emu on slot/partition 10 and above.
Well conclusion .emu will only write to slots/partition 0-9 (even in ps3gen)
Must use DIRECT output after build in ps3gen to write on slot 10 and above. (.emu can be renamed to .iso and extracted via mounting program to build again to direct output)
My test with Inversion (cause its small) on slot 254 it mounted in XMB and played.