Cvsup kernel source only?

[Andre LeClaire]

Hello, everyone! With the idea of creating a custom router, I've 
installed DragonFly on an older laptop with limited resources (1GB flash 
drive), and wonder if it's possible to build a custom kernel by 
cvsup-ing the kernel source only? This was possible with FreeBSD 4*, but 
all the info I've found describes getting the entire source tree for 
Dragonfly, which wouldn't fit in the space available.

Thanks!

Andre