scatterplot3d and box3d

I created a 3d scatter plot and am trying to change the color of outer box
lines with box3d.

Anybody can help me to figure out how to do this?

My example is:

library(scatterplot3d)
x=seq(1:6)
y=seq(7:12)
z=x*2
scatterplot3d(x, y,z)

Thanks.

Xin