Nobody told you to override mIRC's drawing commands. The suggestion was to *add* commands as any script would and implement *new* custom drawing commands through your dll.
There's no reason why you need to issue *ANY* of mIRC's /draw commands to get what you need. In other words, just because mIRC has /drawrot, for example, doesn't mean you HAVE to use it. Implement your own /draw command: /draw3drot that would take similar parameters and perform rotation. Same for /drawdot, etc.
It will save you the time of having a pointless technical discussion about trying to hack into mIRC's internal data structures, or overriding message procs to get what you need. In short: it's simpler.
DCX does the same thing. Although the script is an "extension" of dialogs, it doesn't actually override any /dialog commands or events. Instead, it creates a new set of commands and events (/xdialog, etc.). There's a reason they didn't bother hooking into all of mIRC's controls. In the end, users don't care. A command is a command, whether it is built-in or added by script. You should take a page from DCX development and do the same.
