If coming from Rawalpindi, one can take Daewoo bus from Rawalpindi Daewoo bus station to Faisalabad directly. You can also get Daewoo bus from Lahore.
Trip to Faisalabad from Lahore is about 2 hours plus and the schedule is quite frequent. If coming from Rawalpindi, the trip will take 4 hours.
Faisalabad is easily accessible by bus from numerous cities in Pakistan. I took a bus from Lahore.
The bus system in Pakistan is not like that in the US, there are no large companies like Greyhound, other than Daewoo, and subsequently no real route networks. However buses can be found all over the country going to numerous destinations.
For my trip, there is a large "bus station" in the heart of Lahore from where numerous buses leave. I simply went there and asked about the next bus to Faislabad and was directed to it. The ride was about 3 hours, with a stop at some village on the GT Road.
The ride was rough, and the seat was uncomfortable, but it couldn't have cost me more than $2.