Um, no, there's not a way to make B13 springs fit an S13. Totally the wrong diameter for the front OR the rear, not to mention the spring rates being weird. Don't know who told you that but I'm not sure I'd trust their knowledge any more.
I know that B14 fronts won't work. B14 rears and S13 rears might be the same diameter but again the spring rate will be wrong as far as I know and I bet the height is different as well.
Why wouldn't you just get S13 springs? You know they'll fit...