[LabourofLove]

When was it transplanted last?? If it was within the past two years, it's likely NOT regrown a huge root system and will actually take to being transplanted again better than if it was moved MORE than two years ago.

9' tall is not all that big. Prune it down by 25% (take 2' off the top) and if it has lots of multiple stems, take out every 5th one 6" above the ground (induces new basal growth to keep it from being too leggy). All of this pruning also makes for less 'shock' when the actual transplanting occurs (less leaf surfaces to sustain while it's getting over the stresses of transplanting).

Anyway, a lilac that size can be hand or machine-dug. Try not to let the local backhoe operator do the digging - hire someone with a real tree spade. The local backhoe guy will tear the living bejesus out of the roots and probably tear bark on the lilac, too.

Be sure that the roots DO NOT dry out while the plant is out of the ground. If it's going to be out of the ground for more than a day, cover the roots with burlap or towels and soak 'em down. It isn't that the root ball needs to be saturated, just that the small, feeder roots are very susceptable to damage from drying.