After a look at the G70 manual, I don't think there is a way from the keyboard.
You will have to disable Song Start and Midi Clock messages from Logic (I'm a Cubase man, so you're on your own, there! Maybe the Logic Forum can help?)
A post at
http://www.selskabsmusikeren.dk might get you some help, too.
There's a new Style Lockout feature in the forthcoming OS 2 that MIGHT help, but not sure, yet.
[This message has been edited by Diki (edited 09-24-2005).]