I have no experience with any Java packages that make it "easy" to write PostScript files from Java applications. How "easy" it is would depend on what kind of files are being created by the application. Text files with different font faces and sizes? Some adornment (lines, etc.)? Graphics figures? Embedded graphics files? What?
I'm a little curious:
What kind of package (if any) was used to make it "easy" to write pcl files? What was its API? Knowing that might make it easier to find a functional replacement for creating PostScript or PDF files. If it was all raw, brute-force PCL-specific stuff embedded in the application, well, I can't think of any way to help.
However...
As a non-Java solution, similar to your previous method, you could try GhostPDL from here
GhostScript GhostPDL Download page
I used it for a project that had a lot of PCL5 files and I needed something viewable and printable on my Centos Linux workstation. Using that program to convert pcl to pdf worked (most of the time). Did not have access to source to see how the original project actually created the pcl files. (It wasn't Java.)
Building the executable was a snap ("./configure" followed by "make") with GNU gcc version 4.1.2. Never had to touch any of the C source files.
There were a couple of flaky pcl files that, for some reason, created pdf files that could be viewed with Adobe acroread, but wouldn't print. (All of them that I had would print OK from kGhostView. Go figure.) Files had various graphics shapes and adornments as well as almost-chaotic fontamonium and color and stuff like that.
There are scripts supplied in the "tools" directory so that the conversion from pcl to pdf is easy to automate, and there is a Java-based viewer, Gview, under the tools/viewer directory for rendering a pcl file to the screen without having to convert. (You can print from Gview if you want to, rather than converting to pdf and viewing and/or printing the pdf file.)
Cheers!
Z