you can ...
if the altec is just a full range driver (no tweeter), then a tweeter with a capacitor should work but ... I wish I can say everything, so here is my suggestion
at 17khz, you will need basically about 1uF capacitor (cut of at 20khz actually), mga 1.33uF for 17khz (unusual cap value, PARALLEL 2 of 0.68uF cap will do the trick, then reverse the polarity to the tweeter). At the same time, tweeter are typically of much higher sensitivity than typical mass market full range, so you need a resistor (also in series, desirable than just caps alone). start from about 100ohms (5W, the rectangular white one), then decrease or increase to your desired sonic balance. With the resistor, there will be no issue on the amp (it will not be able to see the tweeter because of the resistor - kinda like that). Further, you may need a 16ohm (5W resistor) in parallel to the series connection of cap/tweeter (to effectively cut off at 17khz).
+----1uF----tweeter----+
---100ohms----+ +------- (positive terminal)
+------16ohms---------+
Lastly, IMO, 17khz is not that bad really.