Doing your own service doesn't void your factory warranty, but it can happen...
The 600 mile service is mainly an inspection:
-Engien Idle Speed
-Brakes and Clutch System
-Nuts, Bolts, and Fasteners
-Steering Head Bearings
-Replace Oil/Oil Filter
You can do this yourself and not void the warranty. If you take your bike to a dealership with a warranty issue they shouldn't say anything. If after the bike has been evaluated Honda asks for service records, this is the critical part.
If you do your own work on your bike you should keep a record of what was done, dates, miles, and the reciept of replaced items.
If you don't have these records and Honda request them from the dealership, then you could have your warranty voided. (So if Honda doesn't ask for records there shouldn't be an issue)