If you’re concerned about ensuring correct dosing and you’ve found broken down dosages for injecting, you should bite the bullet and inject the correct dose. It’s a medication that’s intended for injection and while some drugs can be used through different routes and work, others do not. Most birds actually react less to a quick subcutaneous or intramuscular injection than pinning them down and forcing a dose into their mouth. If you’re having trouble finding dosing information for a specific route, usually it’s because it’s not a good choice.

Some drugs are definitely NOT safe to give by any other route than what is labeled so you have to be careful or you may do more harm than good. (Micotil, anyone?) Not trying to ruffle any feathers but given what you’ve said of your schedule, the best way to ensure proper dosing with the least amount of time and effort is to inject it.