I was looking for a way to install windbg as postmortem debugger so that everytime any process crashes or exits unexpectedly, windbg is launched automatically and I can take a look at whats happening there!
Windbg has special command line option for installing it as postmortem debugger. Use following command,
C:\Program files\Debugging Tools for Windows>windbg.exe -IS
This will set AeDebug entry as,
Path\windbg -p %ld -e %ld -g"
If you want to associate .dmp, .mdmp or .wew extensions with windbg (so that when you double click on them in explorer, windbg gets opened automatically), you can use -IAS option.
PS: command-line option -I is for installing windbg as post-mortem debugger. [S] command line option is optional, if used it will not display any success message after executing the option (silently installation), only error messages are propogated..