Is it possible to 'carry' the <%category%> tag across several pages?

What I had in mind was that a user navigates his way to the appropriate category, clicks 'Add my Site' or similar, gets taken to a service selection page and THEN goes to the 'Add my Site' form which calls add.cgi.

Hence <%category%> would have to go via the selection page.

My directory is quite large, so I can't use the 'drop down' option to allow the user to select the category that way.

Is this easy to do?

Thanks.