Hi Juan,

I use the Cruise CoG that is calculated in the PER INIT page on the lower right.

And one important item I forgot to mention - to make use of the fmc and autopilot LNAV modes, you first have to align the IRS on the overhead panel. Luckily, the guys from CS have shortened the time it takes for the IRS to align. So befor you start programming the fmc you have to set the irs switches to align and -after the align lights go out - switch the irs to nav.

Regards,
Werner