If you type in the shell:
blc picture.iffThen picture.iff is converted to "picture.blc" and "picture.col"
If you type:
blc ram:#?.bshThen all files ending with ".bsh" in ram: will be converted. PLEASE NOTE that you must have BLC in C: for this to work!
If you have BLC in C:, then you can use it from BL's brush menu: "Load IFF Brush as Copy". This is the easiest way to load IFFs!