All you need to create a rotational matrix is the pitch, yaw, roll, and the ability to perform matrix multiplication.
First, create three rotational matrices, one for each axis of rotation (ie one for pitch, one for yaw, one for roll). These matrices will have the values:
Pitch Matrix:
1, 0, 0, 0,
0, cos(pitch), sin(pitch), 0,
0, -sin(pitch), cos(pitch), 0,
0, 0, 0, 1
Yaw Matrix:
cos(yaw), 0, -sin(yaw), 0,
0, 1, 0, 0,
sin(yaw), 0, cos(yaw), 0,
0, 0, 0, 1
Roll Matrix:
cos(roll), sin(roll), 0, 0,
-sin(roll), cos(roll), 0, 0,
0, 0, 1, 0,
0, 0, 0, 1
Next, multiply all of these together. The order here is important. For normal rotations, you will want to multiply the Roll Matrix by the Yaw Matrix first and then multiply the product by the Pitch Matrix. However, if you're trying to "undo" a rotation by going backwards, you'll want to perform the multiplications in reverse order (in addition to the angles having opposite values).