The recolor needs to change the artwork from blacks/whites/grays to reflex blue + tones
And what is it exactly you are having problems with that you can't do with a simple brightnes based gradient or a pre-defined set of swatches? You need to clarify and explain better. simply sounds liek you have never used the tool or even read the help...
German user interface, but should work for you. Just click on the same button according to the layout of stuff on the screen:
You may try to use the grayscale image for an Opacity Mask and see whether that is satisfactory as an additional masure. You may:
1) Create a larger reflex blue rectangle beneath the image;
2) Select both and in the Transparency palette flyout tick Make Opacity Mask, with Clip and Invert Mask ticked.
If the image is a grayscale tif colored in illustrator then recolor artwork should correct this.
Otherwise you will can in Photohsop resave this as a grayscale tif, replace image in illustrator, and color in illustrator using a swatch of reflxe blue.
Alterantively you could change the grayscale image in photshop to a monotone, and choose Reflex blue.