If there is a color picker for hue/saturation, I’ve never found it. Inlife? Where?
Once you turn on colorize, you can set the color, but as far as I’m aware, only by setting the Hue, Saturation and Lightness values.
So you need to convert hex to HSL. Try here… http://serennu.com/colour/hsltorgb.php
Alternatively, you can just add a Tint or Tritone effect from the Effect -> Color Correction menu. These are a bit more intuitive.
If you’re feeling bold, you could try out Change Color or Change To Color from the same menu.
More color correction info here… Adobe online help - Color Correction
You can also tint a whole scene by adding a new solid Layer -> New Solid of the appropriate color, moving it to the top of the layer stack, setting its blending mode to color and then adjusting the opacity. This has the effect of tinting the whole comp to a greater or lesser extent.