Basically, if you can envision a sql select where all the data that you want to display is on one line, then it can be done, either use a stored proc or joining to the tables directly.
If you can't imagine the sql select, then create a store proc and manipulate the data as you want, then select the data. CR will see the manipulated data as a table, and will display the values as you desire.
The biggest problem is if the joins between tables result in more records...where some values appear duplicated, this sometimes can lead to a confusing report.
HTH