If you are a programmer, it is very easy to create your own fade modules.  A fade module takes two parameters, a bounding rectangle and a pattern to fade to.  (Shutdown FX always uses the entire screen and fades to black, but the fade module really couldn’t care less.)  Make a new project and set it to compile as a PROC 0 resource, type 'Fade', creator '2fx2'.  The resource attributes are not important except that the resource can not be purgeable.  The actual function declaration in C looks like this:

pascal short main(Rect boundsRect, Pattern *thePattern);

Fades do not need to be written in C.  They can be written in any language that supports the Pascal calling convention, including Pascal.  The fade should return 0 if there is no error, or -1 otherwise.  Fades can move memory (like anything that calls Quickdraw routines), but they should not have global variables unless you set up your own A5 world.  To make fades run at the same speed on any Macintosh, #include "timing.h" (included with the source code to Shutdown FX), call StartTiming() at the beginning of your inner loop, and call TimeCorrection(n) at the end of your inner loop, where "n" is the number of ticks to delay.  "timing.h" also includes a procedure ScrollTheRect(...) for safely scrolling subrectangles on the screen.