Execwait equivalent for System::Call ?

Is there Execwait equivalent for System::Call? What I'm trying to do is to include a DLL in the installer, extract and call it during the installation and delete the DLL once we're done. Using just System::Call the DLL is usually in use when NSIS reaches the delete command, thus failing to remove it.

You can Delete instruction after Execwait?
See Execwait for remarks and return values...

And for ExecWait equal in System::Call you'll have to code..and a lot

How on Earth did I miss that? :| Thanks!