Scott
if you want to use a particular aperture setting, why not use "aperture-priority"
mode ?
Shooting in manual, you get the best of both worlds because you can control both aperture & shutter. As long as you understand what the EV meter inside the viewfinder is telling you, and adjust your settings accordingly, you should be fine.
Once you get to know how the D70 will meter particular scenes (either with large bright or large dark areas, you learn to accomodate for this whilst watching the EV meter inside the viewfinder. When the meter is "centred", the camera is metering the scene the way it thinks works best. To control your Exposure Compensation "manually", adjust your shutter, aperture OR both slightly to either over-expose or under-expose to the amount you feel will give you the best exposure (for what you are trying to achieve). By taking note of which way the meter is moving (from the centre), you will know what is going on.
From here, try taking some shots, then making some minor adjustments and take a few more. When you get them on the PC, have a look at what settings worked best and what didn't. You'll soon begin to notice what is working for you and from there, you'll be happy and at ease to stick the D70 into M
mode.
Of course, sometimes A or S
mode is handy or makes life easier (if you don't have time to reshoot or need to make very fast changes "on the fly"....although shooting in manual is still possible...it just becomes more of an artform to nail it "every time".