In the July 1999 DDJ there was an article that mentioned an x509 certificate browser prototyped in Squeak (2.3(!)). Maybe you can find something useful in the code that goes with it.

I was able to file it into a 3.4a-5125 image, open a cert browser (in an mvc project), and (with slight hiccups) display a certificate exported (in base64) from IE.

Article is here:
http://www.ddj.com/documents/s=901/ddj9907c/9907c.htm

Example screen shot is here:
http://www.ddj.com/documents/s=901/ddj9907c/9907cf7.htm

Some (java) listing is here:
http://www.ddj.com/ftp/1999/1999_07/x509.txt

Code (mostly java, but look for x509.st in the archive) is here:
http://www.ddj.com/ftp/1999/1999_07/x509.zip

Joern