I will be doing something far more elaborate to solve this later on but here is a simple version for you since you only have tow orry about 2 alts.

on both alts unbind the left and right arrow keys (normally used for turning left and right) now on 1 alt rebind the left arrow key to turn left, on alt 2 rebind the right arrow key to turn right.

now when you need to turn them hitting the respective keys will turn the alts. If you want them to move together and dont care about being able to do them seperately dont bother with any of the above and just use the arrow keys to turn them.