It should be relatively easy and pain free - what size is the network - i.e. how many routers and max hops between them. How many RP's will you require and for what groups? Do you want any RP redundancy? if so do you want to run Auto-RP or Anycast?
Depending on the importance of your multicast traffic I would run either Auto-RP or Anycast. Anycast fails over faster (as long as you have a fast routing protocol such as EIGRP os OSPF) but Auto-RP is much easier.
For Auto-RP these are the steps I would take:
1. Change all your interfaces to Sparse-Dense Mode
2. Enable the Auto-RP Listener service on all your routers (check whether this is feature is available in your IOS)
3. Enable Auto-RP on your selected RP routers (Candidate-RP & Mapping Agents)
4. Verify the RP Routers are sending the Auto-RP Announcements to the group 224.0.1.39.
5. Verify the Mapping Agent Routers are receiving the Auto-RP announcements
6, Confirm your multicast routers are receiving the Annoucements from the Mapping Agent(s) for the Auto-RP-Discovery group (224.0.1.40)
7. Confirm all your known groups are registered to the RPs and are operating in Sparse-Mode
8. Change all your interfaces to Sparse-Mode
Done
