As long as you can dig through the frozen layer, you can plant the bulbs. That is usually preferable to the alternative, which is not to plant them. You may want to mulch over the planted area to prevent the frost from going deep too quickly. You should need to water only if the soil is quite dry.
If it's not possible to dig in the soil any longer, you could pot up the bulbs and stick them in a refrigerator or hold in a cold spot just above freezing for them to get their cold treatment.