Here is the link to the documentation on the <html:link> tag.
Here's the part that explains how to provide multiple parameters:
If you prefer to specify a java.util.Map that contains all of the request parameters to be added to the hyperlink, use one of the following techniques:
Specify only the name attribute - The named JSP bean (optionally scoped by the value of the scope attribute) must identify a java.util.Map containing the parameters.
Specify both name and property attributes - The specified property getter method will be called on the bean identified by the name (and optional scope) attributes, in order to return the java.util.Map containing the parameters.
As the Map is processed, the keys are assumed to be the names of query parameters to be appended to the hyperlink. The value associated with each key must be either a String or a String array representing the parameter value(s), or an object whose toString() method will be called. If a String array is specified, more than one value for the same query parameter name will be created.
[ August 13, 2006: Message edited by: Merrill Higginson ]