  TGAtoN64 is a very simple, hacked together solution for making targas into N64-acceptable binaries.  It only accepts a small number of possible targa images, expects them to be in the direction they're already supposed to be in, and doesn't bother with RLE encrypted files.  (I told you this was hacked together, right?)
  It does autodetect the type of image you give it and tell you what's wrong with it if it isn't one it can accept.  For the most part, this thing accepts black & white targas and spits out N64 binaries.

+ Option 1 is intended for a black & white image that has transparency and spits out, for all intents and purposes, an exact duplicate of the file minus all the targa headers and footers.
+ Option 2 diminishes a black & white image with transparency to the funny 4bit mode.  They aren't used that often.  Mostly these occur in fonts or, in the case of Animal Forest, the title screen characters.
+ Options 3 and 4 output intensity only images, or in other words black and white.  They are for greyscale targas with transparency present, or in other words 16bit intensity-alpha.  You can use either the 'color' value if it is grey vs. black or the alpha to ignore how grey it is, such as with white on transparency or black on transparency.
+ Option 5 only works with greyscale targas, usually b/w output, that happen to already be 8bit intensity and need to be diminished to 4bit.  

  Source is included, in case you want to make a useful tool out of it.

-Zoinkity
