How do I add a serial driver?

[Paul J THACKER]

I'm porting ECOS to a new platform, based on the ARM926. I cloned an 
existing platform and got everything to compile, but I can't figure out 
how to add the serial driver.

I cloned an existing driver and added it to my cdl files. It shows up in 
 Build->Packages, but when I try to add it, I get a message that says 
"Add and remove hardware packages by selecting a new hardware template".

I tried a couple of other platforms with the same result. I'm clearly 
not understanding this process. Can anybody help?

Thanks,
Paul