Regardless of how experienced employees are with new social software, everyone responds to the following: free lunch and half days.
The company could have a digital newsletter about the implementation time frame of the platform where it could list dates of Friday seminars, which include a free lunch and half-day should the employees attend. This will incentivize employees to learn about the system and expand upon the company moving to a more social culture.
I currently intern at a talent agency that implemented a new IM-ing technology; to get employees involved and on the same page, they provided free lunches at monthly seminars (one Friday a month for three months) to explain how to use it. Even the two presidents of the agency attended. Additionally, they incentivized people to go to the seminar by offering a half-day to go home early after attending the seminar.This will hopefully translate to employees their value to the company and empower them to use it. Also, relay at the lunches how the system will add value to their daily work and the company by proof that top executives are using it too. I also think getting multiple employees together will create an environment of sharing, trust, and transparency. Long-term adoption would be assured by the set deadline in the introduction newsletter and get across to employees that they can learn at their own pace until the target date. Ultimately, the company is moving in a social direction that employees will need to join.