[magick-users] How to change the color of an transparent png

[froesi]

Hi guys,

I've a vector graphic with a single color as an png file. To look smooth the
graphic has  an anti aliasement.
I tried something like this

-fuzz 4 % -fill "#FFFFFF" -opaque "#000000", but the thing is, that not
every pixel of the graphic will be conerted to the new color.
I need something like this

http://www.lsus.edu/sc/math/rmabry/imagemagick/multireplace
->>"Replace black with blue #0000ff:"

I've no idea how to get this. It would be really great, if someone can give
me a hint.
Thank you,

cheers
froesi