To install the Spectral Toolbox routines requires
a few steps... it's not very hard, but does require
installing either Max Runtime (free from cycling74) 
or Max/MSP (not free) and some java routines. 
These instructions work for both Macs and PCs,
but unfortunately, not for Linux (because Max/MSP
is not available for Linux. Sorry.)

Here are the instructions:

(1) Go to 

www.cycling74.com/downloads/maxmsp

Go to "current version" and then click on 

"max/msp runtime" for your computer (Mac or PC)

Install Max/MSP runtime following the normal
procedures (i.e., follow the on-screen instructions).
This will create a folder called "MaxMSP Runtime"
in your applications folder (if you're on a Mac)
or in C:\Program Files\Cycling '74 (if on a PC).

(2) Put TransFormSynth and other routines
from the Spectral Toolbox somewhere on your hard
drive where you can find it when you need it.
One possibility is insider the "MaxMSP Runtime" folder,
but anywhere will do.

(3) Unzip java-classes.zip 
If you're on a Mac, put the contents into

Applications/MaxMSP Runtime/Cycling '74/java/

If you're on a PC, put the contents into

C:\Program Files\Cycling '74\MaxMSP 4.6\Cycling '74\java\classes

It is important to use these folders because otherwise
the program won't be able to find the necessary java routines.

(4) To start the program using Max runtime, double click on the
*.mxf icon. (The first time you may need
to tell Windows to 'Open With' MaxRT.exe. On a Mac,
you might similarly need to go to info and choose open with
MaxRT. Some people don't need to do this).

(5) Once the routine opens,
push the "audio on" button. If using the TransformSynth,
click on "random sound and patch" (or you can choose a 
sound and a patch from the little menus).
Play notes using your computer keyboard.
Switch the continuum and you can use MIDI-in,
can specify tunings via scala files, 
and a bunch of other things. PUsh the little
blue i buttons for information/help.

(6) Troubleshooting. What if there's no sound?
Go to (on a Mac)

Applications/MaxMSP Runtime/Cycling '74/patches/editors

or 

C:\Program Files\Cycling '74\MaxMSP 4.6\Cycling '74\patches\editors

and drag "DSP Status" to the Max runtime icon to open it.
Turn audio on and choose a core audio driver (if you're on a Mac)
or whatever your favorite audio driver is.

What if the sound stutters?

In the DSP status (see above), try different values of 
"signal vector" and "I/O vector" size. Generally, 
larger values cause less strain on the CPU.
If you must, you can also try reducing the sample rate.

If you are on a PC that does not have java, you'll need
to download it from here:

http://www.java.com/en/download/index.jsp

Also the program requires Quicktime to be installed - available here...

http://www.apple.com/quicktime/download/

C:\Program Files\Cycling '74\Max Runtime 5.0\Cycling '74\interfaces

What if the sound stutters?

In the DSP status (see above), try different values of 
"signal vector" and "I/O vector" size. Generally, 
larger values cause less strain on the CPU.
If you must, you can also try reducing the sample rate.