Solaris Common Desktop Environment: Advanced User's and System Administrator's Guide
To Change the Logo
Set the Dtlogin*logo*bitmapFile resource in Xresources.
The logo can be a color pixmap or a bitmap file.
The following example uses the Mylogo bitmap as the logo:
Dtlogin*logo*bitmapFile: /usr/local/lib/X11/dt/bitmaps/Mylogo.bm