So, you're wondering how to unhide or unlock hidden attributes on rigs like rotation and scaling? Well, before we begin, I should probably put my "TD-hat" on, and warn you that you should be careful when doing this. It's not dangerous or anything, but normally riggers lock their attributes precisely because they don't want their animators messing with them. You're free to unlock them, and in the context of Animation Mentor and such it's absolutely fine, but if you do it on a professional production of any sort and your riggers find out, they'll probably murder you. Anyway, warning over, let's get unlocking!

Step 1: Open the rig in Maya, select the object you want to modift, and then right click on your channels control. A menu should pop up:

Step 2 is to look for an entry in the menu called "Channels Control". Autodesk seem to enjoy moving it around, so you might have to dig around a bit, but I promise you it's definitely there!

If you select the menu option, a window will pop up. This window lists all the attributes on your currently selected object, and shows you whether they're locked or hidden or not. So step 3 is to find and select the attributes we want to unlock and unhide (rotateX, rotateY, rotateZ and if you want stretch as well then scaleX, scaleY and scaleZ too). Then our fourth (and final!) step is to click the "<<< Move" button to move the attribute from the "Nonkeyable Hidden" column to the "Keyable" column.

And that's it, animate away! Hope this was helpful, please feel free to drop me a line or leave a comment if you get stuck