Any good graphic tools should support conversion of colors to their corresponding hex values, like PaintShop Pro.
Note that this will only give you RGB, UnleashX needs ARGB, so you'd have to add one for the alpha (A) or transparency. For transparency, it's (0 to 100%) * 255, then convert that to hex. For example Red is 255,0,0 in RGB converting this to hex would give you FF0000. For a 90% opacity, 255 * 0.9 ~230 = E6. Final value is E6FF0000.
By the way, thanks to all skinners. You people are doing an awesome job and you never ceases to amaze me. What does it takes to become a good graphic artist? I really envy you with all that creativity. Undoubtedly, you helped UnleashX a lot. Thanks for the support