Letting off a few nukes could slow climate change a bit right? I vaguely recall that all the dust kicked up by the hundreds of tests in the 50s and 60s had an effect.
But volcanic eruptions that cause a winter like that tend to be quite a bit more powerful than your average nuclear weapon. More importantly, not all dust is created equal. Sulphur containing compounds tend to have the biggest cooling effect. One neat (in a terrifying sort of way) geo-engineering idea is continuously injecting large amounts of sulphur dioxide into the stratosphere.