Main thing, make sure the pole your mounting it to is exactly plumb, this is important for the round(any) dish, but even more so for the 3lnb dish.
Make sure you rerun install setup on all receivers to use the Oval/3lnb dish and not the Round. Keep in mind the numbers for Az, Elevation, and Tilt are just baselines, they aren't exact.
Maybe this will help, it's the official directv 3lnb dish install guide:
http://www.directv.com/learn/pdf/12429_00_AntennaManual_1D.pdf
Use the 101 sat as the initial satellite for aiming, (in your receivers signal meter menu make sure 101 is the active one).
If you are using your receivers as the sat/signal finder for adjusting the dish, make sure you give each adjustment 5-8 seconds (or so) before assuming there is no signal, it takes that long for the receiver to lock into the signal, i.e. changes to signal readings are not immediate on the receivers.
A good way, is to adjust the dish by the numbers then tighten the bolts, then watch your signals, and use your thumb to _gently_ 'move' the dish one way or the other, while holding the dish with your thumb(steadily) watch the signal meters, (remember give it 5-8 secs to lock on), (if you get a signal when you thumb it, remove thumb, loosen bolts, and move it in the direction of where it was when thumbed, and retighten the bolts, if you get signals in low/mid 90s or higher, that adjustments done, move on to the next)
If you get no signal, loosen the bolts in question, and move it a few degrees, tighten bolts, wit 5-8 secs, if no signal still, try the thumb thing again, etc. NOTE: The thumb thing works for Az, and Elevation (i.e. don't try and thumb the Tilt), the Tilt should be fine at the settings stated by your receiver/website.
Good luck.