This script can copy and paste tangents of knots and knot types. If more than one tangent selected on spline it takes the tangents of knot with less index. If more than one tangent selected on several splines it pastes tangents to knots on ONLY ONE spline with less index.
place Copy_Paste_KnotVector.mcr to 3dsmax7UIMacroScripts
In Customize>Customize User Interface u can set hotkeys or add following options to quad menu: 'Copy Knot Vector(Spline)' and 'Paste Knot Vector(Spline)'. Look for it in 'Editable Spline Object' category.