You can buy IndexAssistant from RegNow, for just $10:
To install and use IndexAssistant, you first need to have obtained and installed the demo version. When you receive the file containing the full version of IndexAssistant, execute the self-executing file and unzip the files into the directory where you placed the files for the demo version. Then go to that directory, open the IndexAssistant manual in Word, and follow the directions for installing the full version, including the directions about macro security settings.
Two notes about security:
1) If the attachment you received by email when you purchased IA has an extension other than .exe or .zip, your security software (e.g. Norton AntiVirus or Zone Alarm) may have changed the extension from .exe to something else to protect you from viruses. In this case, change the file name so as to save the attachment as an .exe file. Then run it to unzip it.
2) Installation is done through Word macros contained in the manual,
and IA is programmed in Word’s macro language. To install and run IA,
you therefore need to set Word’s macro security settings to medium (Tools>Macro>Security
in Word 2000 and higher; macro setting in Tools>Option in Word 97). If your
settings have not already been set to medium, then you will need to reopen
the manual before trying to use the install process below. And when
you open this document, you need to tell Word to enable the macros in it.
Note about Word macro security: On the medium security setting, Word will trust macros contained in your user templates or start up template directories, which is where IA will be installed. For all other documents Word will ask whether its macros should be enabled. These are precautions against macro viruses. Do not install any Word documents that you do not trust in your user templates or start up template directories.