Here is a excerpt from the User Guide for the 3500 model switch. [IMAGE]  The front panel contains 24 RJ-45 ports number 1-24. The upper row of ports is marked with odd numbers 1-23, and the lower row of ports is marked with even numbers 2-24. In addition, the front panel also contains ports G1 - G2 which are fiber ports and ports G3- G4 which are copper ports. Ports G3 - G4 can either be used as stacking ports, or used to forward network traffic in a stand-alone device. I can spend sometime looking into this.  At this time it does not look like that is possible. I will update the post with any possible information that I can come up with. 
I've noticed under System, Advanced settigns, general settings there is a stacking port entry with the ability to select Copper Ports or Fiber Ports.  Can the 35xx switches now use Fiber for stacking ports? Has anyone tested it?
3548 Stacking ports... Fiber?