Crap, I don't know where I got the 6 from. Probably the same place I got the OFD?
Is this a DX7s? Will it program like one? Not familiar with these Spectrum radios at all, but I do have this one. I keep it so I have something that will bind to an MCPX heli I like to beat on regularly.
If your radio programs like mine, just set up a new model (that way you don't screw up the setting you already have, allowing you to return to it if necessary), and make it a heli. While you are in that section of setup, set the swash plate type to single servo (not 2, 3, or 4!). Then save/exit.
When you turn the radio back on and select this new model heli, you will now have the throttle curve you're looking for, and your ail., elev. and rudder will be unaffected. They'll set up exactly as they would if it were a plane.
I set a curve up in the throttle that looked OK but it's definitely not tested? Try 0>12>24>48>100
That curve could leave you with the opposite problem you have now, with the stick moving too far to get much of a power change in the first part of it's movement. If that's the case, maybe try 0>20>35>60>100 ?
If you're using an opti switch on an aux channel, it may require some messing around to get that going again? You could set it up as a gyro, and assign a switch to it? Just be aware that as a heli, one of the channels is going to think it's collective pitch, which of course you aren't going to use. You probably already know you can go to "monitor" and see what's happening on each of your channels to help figure stuff like this out....
Best of luck, -Al