External Clock for DE2 board

You can instantiate a PLL primitve and connect your custom logic to it ... for example, I posted a design to this thread that creates a PLL and connects to the scan chain ...

http://www.alteraforum.com/forum/showthread.php?t=46527

In the case of the DE2 you could use the 50MHz as the PLL input and then configure the PLL for one or more outputs with different frequencies. Use the PLL in the IP catalog to get a sense of what is possible. The GUI just helps fill in the generics on the component.

Cheers,

Dave