KDE-Artists.org has a section where KDE developers can request new icons. All you have to do is register at the site and start a topic in the Application Projects board on our Kollaboration forum.
Please include any ideas you have for the icon like symbolism, colors, etc. You could even attach a picture of your current icon and a link to your project's website. The more details you include the better. Then our artists can submit their icons to your thread and you can pick the one you like the best. Another benefit is that other kde-artists can give suggestions to make sure your new icon complies with our current Crystal standards and looks really cool!
Don't forget to check back often and particapate in your new "Kollaboration".