You can set it manually, or you can determine the de-rated takeoff thrust.  The EPR you cite seems very high to me!

I use a takeoff calculator created for a previous 767 and it seems to work fine.  It is available free online.  You should be able to find it without too much difficulty.  I typically see 61 or 63 degrees... somewhere around there.  That's what I put in the FMC and that's what I see on the upper EICAS, and that's what the engines power up to.

Using that, you should get something less than 1.55.  You're taking advantage of your runway length and atmospheric conditions to save some wear and tear on your engines.

I don't use manual settings.  Just set it through the FMC, make sure AT is armed, throttle up to 1.40 EPR and hit the EPR button, then watch thrust advance to the EPR setting on the upper EICAS.

The manual is less than helpful here, unfortunately.  There is a tutorial movie available via a sticky on the forum.  Put the left knob to the middle, skip the brightness knob, and push the third knob's middle in.  The default should be 1.55, I'm thinking, and that ought to work anyway.  I can't imagine needing 1.7 something to take off from most airports.