can I create my own icons? None of the ones in the package work for my design.

We have a 400,000 member creative community and are launching our new site (we get about 1.5 million visits a month) and are incorporating sharexy...we have already set it up throughout the wordpress side but we have to use our own icon pack.  Can you let me know how this can be done please?  Great work by the way!  Looking forward to seeing where you all go.