1. Do you have a shop manual at hand? (Which is NEVER a bad thing when attempting a major repair such as this?)
2. Have you positioned the engine as directed by the aforementioned shop manual?
Have you then accessed the IP drive gear from the front, and removed the bolt retaining it to the IP shaft, then freed the gear as the shop manual directs?
If NOT you are in serious need of a shop manual before proceeding/destroying the poor innocent machine!