I do not quite understand your question. It seems the posting title and content indicate different things.

From the posting title I understand you have some musical material, and want to import it into iRealPro.
There are tools that may be helpful, but usually it boils down to hand work (even with the tools).

In the posting content, however, you mention that want to take advantage of adjust assembly, page turning, etc. Since iRealPro cannot do these things I get the impression you want to take iRealPro songs out of iRealPro and import into another program that can adjust assembly, page turning, etc.
There are tools that may be helpful for this, too.