As it is currently set up, it is not possible to change the color of the text labels for ArcExplorer's mo2legend.ocx. However, a slight modification will cause the text to be the same as the specified ForeColor.
Edit the following line in the LoadLegend sub for the MO2Legend.ctl file:
'Display the Label
.AutoRedraw = True
.ForeColor = UserControl.ForeColor '<- was f_TextColor
After recompiling the text color can be changed by setting the ForeColor property.