Use IRS for Lat-Long. Plot it on the Jepp say every 10 minutes or so. Since you would still have a Track Line available, you can use the ND to navigate using the following method:
*Set the Track Required in the MCP Course Window.
*Set the ND to CTR VOR mode.
*In the ND you will have the hollow Course needle and the white track line. The course needle is your Track Required[TR]. The Track line is your Track Made Good [TMG]. Use HDG SEL to turn the aircraft to keep the TMG line
inside the TR line.
*This way you will be able to give wind corrections, make airway course changes etc with a bit of ease.
Hope this helps
