I thought about Josh's post a bit and dug through the Makefile and I see it now. The Makefile is looking for the _clut224 suffix on the file name in order to know it's a 224 color image. By renaming my image (and the assiocated code changes in logo.c/Makefile/linux_logo.h) I can now see my code successfully compile.
I also understand that Josh's changes could be so simple because he was replacing the default 224 color Tux logo with the new one by naming his logo: logo_linux_clut224.ppm (the same name as the previous logo)
My one sticking point now is that I can't seem to get mylogo to show up instead of tux. The code compiles and makes sense, but still Tux remains. I thought it was because the "logo" variable from logo.c was getting overwritten so I went back to the defconfig and updated it:
CONFIG_LOGO=y CONFIG_LOGO_EMERSON=y #CONFIG_LOGO_LINUX_MONO is not set #CONFIG_LOGO_LINUX_VGA16 is not set #CONFIG_LOGO_LINUX_CLUT224 is not set
So everything was removed except for mine, but still Tux is showing up... I'm hacking through the code right now trying to figure out why I can't see my logo, but that's where I'm at in case anyone else has other ideas.