I've taken a look at some EQF files that I made for the purpose. The format is apparently very simple:

1. The file is 299 bytes long.
2. It starts with a text header, which in my case, is 37 bytes long. It is, in double-quotish notation — note the control-Z character:

   Winamp EQ library file v1.1\cZ!--Entry1
   [download]

3. Next is a block of null bytes ("\0") up till the next, final part.
4. The real data is stored in the last 11 bytes of the file: the last byte is for the general volume, the 10 bytes before that are for each of the 10 EQ controls, in ascending order: the first of these 10 for the deepest bass, the last one (right in front of the volume byte) is for the highest treble.
5. The values are 0x20 in neutral position, and are reversed in value: 0x00 is maximum, 0x3F is minimum. So there are 31 positions below, and 31 32 levels above neutral.

Do you know enough by this?