Yes. First, make sure both devices are on the same wi-fi network and iFly is running on both.
Then, on the phone, from the main screen, tap Flight Plan > More Options > Share/Export Flight Plan... > Share across local network..., make sure the "Auto-Share Changes" box is checked, then tap "Share Plan".
On the 740, look for a popup box asking you to confirm you want it to accept the shared plan.
From then on, any changes you make on the phone will be reflected on the 740. (Sounds like you may only be doing a one-time push from the phone to your 740 at the start of the flight. If so, then you could uncheck "Auto-Share Changes" and it'll just be a one-time push.)