I've never used Websphere, but I can safely say that it can perform
evaluation within a tag (not taglib as you mentioned), and it can work
with single quotes. The reason behind my confidence is the servlet and
JSP API compliance that Websphere has. If it works in Tomcat, unless
you're doing something internal to websphere, it has to work on IBM/BEA
or for that matter any certified app server.
<input type='hidden' name='foo'
value='<%=request.getParameter("foo")%>' /> will work - there is
scriptlet in the argument, and I've used single quotes. If it doesnt,
please do post a message, as I'd find it very alarming.
-cheers,
Manish