How to use the clip filters in iMovie

I know how to use the clip filters but I want to tint a movie to a very specific RGB color that is not a part of the preset clip filters. What I've been able to do is turn the clip to B&W, import into Keynote, lay a semi-transparanet color rectangle over the who film and export it as a movie. Would really appreciate a slightly easier method and one where I can precisely control the "tinting" contrast, saturation, etc. Again, I've tried all the sliders and theyre just too limited and imprecise. Many thank in advance.

[Edited by Moderator]