AFAIK, there is special tool to use NetWare resources under Solaris. But I want offer you “low-cost” solution with additional features. You can install small linux-box (on old PC), configured with “full internal IPX support” and install on it ncpfs (package which allow mount NetWare volumes and print to NetWare queues from Linux). Next, simply create “printer” on linux-box, which will redirect print jobs to NetWare queue using nprint utility from ncpfs package. If you create some printers with different filters (using gs package, for example), you can directly print *.ps, *.pdf and other files. Using linux-box as print-relay allow you record quantity of pages printed. This solution allow also printing to the NetWare queue without logging in NDS.
Using diskless computer for linux-box looks like as good idea, but printing process need hard drive for spooling print jobs.
As you know, Linux and ncpfs distributed under GPL, so you do not need to buy additional commercial products.