ADWLauncher: Go straight to default screen instead of requiring a second "home" tap?
I don't think there is a setting in ADW that can do that. I use ADW.EX and I looked through all the settings and didn't see any way to achieve what your are asking for. 

It is, however, open source, so someone could implement the option for this, or you could request it to anderweb and he might add it to an update.