think you need to brush up on colour spaces a bit, sounds like your close to being a bit out of your depth, have a look at how to implement pantone colours if its a "must have"
The color is out of gamut. CMYK equivalent is dull by comparison. No option other than to run a fifth spot color. Pick up a copy of th Pantone fan-out guide that compares the Pantone spot color range with their closest CMYK equivalents.
RGB has a considerably wider color gamut than does CMYK.
Neil
Once you do that, you can see on screen how your blue will react when converted, and make the neccesary adjusmtents in RGB.
And has stated, you wont be able to get a 100% match with 4color process.
That's about as close as you will come in any CMYK space.
Neil
My experience with fluorescent inks (15 years ago) was pretty grim. I usually had to lay down two coats to make it look anywhere near the swatch book.
I would go for the 5th color. The pigments used to create Royal Blue cannot be replicated through any process of mixing standard colors.
I, too, haven't used fluorescent inks in a number of years. Of course, as you say, a fifth spot color is the best color.
As I said, those fluorescent inks "may help slightly". Emphasis on "slightly".
Neil