Thanks nitass, that did it. This is what I have in place, in case anyone else needs it as a reference:
when HTTP_REQUEST {
switch -glob [string tolower [HTTP::uri]] {
"/vd/service/*" {
HTTP::uri [string map -nocase {"/VD/service/" "/change1/"} [HTTP::uri]]
pool Pool_service}
"/vd/forms/*" {
HTTP::uri [string map -nocase {"/VD/Forms/" "/change2/"} [HTTP::uri]]
pool Pool_forms}
"/vd/orders/*" {
HTTP::uri [string map -nocase {"/VD/Orders/" "/change3/"} [HTTP::uri]]
pool Pool_orders}
"/vd/contact/*" {
HTTP::uri [string map -nocase {"/VD/Contact/" "/change4/"} [HTTP::uri]]
pool Pool_contact}
default {
discard
}
}
}