No. The 3550 is designed to route IP only, there are no plans for an IOS release with IPX routing. IPX can be supported using the 'fallback bridging' feature detailed on CCO.
Why not take the opportunity to rid your network of IPX....... IP has been natively supported by Netware since Version 4.0, and we are now on Version 6.0 (about 4 years on....). Even Netware 3.x can be made to work quite easily with IP. Make the effort now and you will thank yourself later.
Andy