Lilacs might be a little too invasive and agressive to have as supports for your kiwis - they send suckers like crazy and might eventually choke out the kiwi plant. It's been my experience that lilacs don't make good neighbours for other plants.

I also have kiwis and have them growing up on an arch-like trellis (it's worth the investment) in a spot that's sheltered from our cold north winds (I live in Northern Ontario). So far they've come back every year(this is the 4th year)

Good luck to you - maybe other members have different suggestions

In my opinion, the kiwi vines are not showy enough to stand out against the green of the lilacs. Assuming they did survive, they would simply be lost in the lilacs. My Arctic Kiwi vines, (one male, one female) grow on very sturdy trellises against a structure, facing SSE so are somewhat protected from the cold NW winds. They were planted 8 years ago, and last season was the first time the male plant showed a few of the pink & white hued leaves. They do green up, almost to the tips each year, and a late spring frost will sometimes damage the leaf buds. They are very slow-growing, and I don't anticipate ever seeing flowers or fruit. I would look for an alternate location, rather than planting with the lilacs.