Very cute, but it fails the second portion of the requirement, which is command validation. ;)
Here's a poor man's implementation. It *should* work for add & modify; don't quite know how to delete entries; this also implies renaming. probably, this would need be_tool_rename & be_tool_delete hooks. Cannot compete in efficiency with slapadd; uses newly added ldifutil stuff (ITS#6194). Please test.
p.