There is no rule that final software must contain the installer. The majority of the software on the berlios/sourceforge/etc. does not have any installer and is available in the form of portable file only. It depends totally on the user how he installs the software into his computer.
How does Windowblinds inject itself? It obviously does so via its installer. Does it also use the same Appinit_Dlls key that yours does? There's a way to make it work.
I already wrote it earlier. WindowBlinds completely replaces the default UX theme service which makes complete rendering non-native. Also, WindowBlinds are the commercial application so there is the demand it has the installer. I am a developer of a library which reimplements blur effect, not a software company which creates complete solution.
And "dangerous"? How? What's worrying you? Are you making a fundamental differentiation between a user setting a registry value then getting a black screen vs. a user running an installer and getting a black screen? I'm not seeing it.
There is a big difference. In case the installer does it, user has absolutely no control what's changed. In case the advanced user does it, he knows what he changed and what to restore back in the case of any problems.
I have one installer prepared for a long time but since this library is very advanced/low-level thing, you can't never ensure that it works properly. It is not just "extract, modify registry value and restart", you must handle various cases such as updates, uninstalls, other software injecting via AppInit_DLLs, not having black screen on uninstall if user changes default theme, etc. etc. many of situations that you cannot handle completely by automatic installer.