Okay, open Regedit
Go to HKCU/*
If there is not a key named "Shell" there, make one.
Inside "shell" make a key named "contig" and modifiy it's value to "Defrag with Contig"
Inside "contig" make a key named "command" and modify it's value to "path/to/contig" "%1"
(include quotes and spaces, and replace path/to... with YOUR path to your copy of Contig)
That will put it in your context menu for files. Now for folders...
Go to HKCU/Folder/shell and do the same except under "command" modify it's value to "path/to/contig -s" "%1\*.*"
OR
copy/paste this into a .reg file and Merge:
(just make sure you edit it to use YOUR path to contig.exe if this is not the same, and omit or edit the folder bit. I have written it to defrag the folder contents and recurse to subdirectories)
REGEDIT4
[HKEY_CLASSES_ROOT\*\shell\contig]
@="Defrag with Contig"
[HKEY_CLASSES_ROOT\*\shell\contig\command]
@="\"C:\\Program Files\\SysInternals\\Contig\\Contig.exe\" \"%1\""
[HKEY_CLASSES_ROOT\Folder\shell\contig]
@="Defrag with Contig"
[HKEY_CLASSES_ROOT\Folder\shell\contig\command]
@="\"C:\\Program Files\\SysInternals\\Contig\\Contig.exe -s\" \"%1\\*.*\""
One could even make an AutoHotkey script that would install/uninstall, but that may be going a bit too far...