Few ways to make mob spawners to say.
1. Vanilla way of making dark rooms and water channels.
2. With DartCraft's Force Wrench, with Shift+Right Click you can pick up vanilla mob spawners. (You can pick up spawners with a PortaSpawner(really expensive), Gravity Gun and/or Portal Gun too, but Force Wrench is cheaper and in my opinion, much more reliable too.)
3. Soul Shards mod. Shove a tier 5 shard into a Soul Cage.
4. With MineFactory Reloaded, make a reliable mob essence farm then use the Auto-Spawner.
The above mentioned methods are for FTB Unleashed. Not sure if if I'm missing anything else, so hopefully someone else can help fill in the blanks.