babi babi,
Have you tried exporting the icon as a .png with transparency into a folder and opening it in photoshop?
You should be able to select the arrow portion in photoshop and cut & paste it to a new document with the same pixel dimensions and a transparent background.
If that works successfully, then use Hue/Saturation (Ctrl+U), select the "colorize" button in the dialog and use the slider control (or text boxes) to adjust the cirle to your liking, then save the circle document.
Repeat procedure to colorize arrow to your liking, and as long as you don't move the circle or the arrow while changing their colors in seperate documents, you should be able to paste the arrow back into the circle document and save.
You should now have a recolored .png image with transparency that you can import into Axialis IconWorkshop.
BTW, I believe Photoshop CS is a free 30 trial download from Adobe if you don't have it.
Hope this helps.