Let's choose to describe all transformations w.r.t. a fixed set of axes:

• translate P to origin: trans(-2,-3,0)
• perform rotation: rot(z,90)
• translate P back: trans(2,3,0)

T = trans(2,3,0) rot(z,90) trans(-2,-3,0)

Rotation about an arbitrary axis

• translate axis k to origin: trans(-P0)
• rotate about x-axis to bring axis k' to lie in xz plane: rot(x,alpha)

The amount of rotation is determined by looking at the projection on the yz plane. Alpha need not actually be calculated; it's sine and cosine can be evaluated directly.
• rotate about y-axis to align axis k'' with z-axis: rot(y,-beta). As in the previous step, we need not actually calculate beta.

• perform the desired rotation: rot(z,theta)
• reverse all the other steps

Overall Transform