There is something on deck for the 4.3 release that's being worked on currently - there is going to be an "Advanced" section added to the conversation page in PCA where additional per user configuration options such as menu repeat times, prompt playback speed, digit timeouts and such will be made available. It is intended that this page can be shown/hidden based on the user's Class of Service setting.
However I don't think anything is planned to hide existing conversation items. To be clear you can't change your "conversation type" from the PCA (i.e. you can't change from Standard to Optional 1 conversation) - but you can change your message stack order, timestamp order, if message numbers are voiced and such. As noted I don't think there are plans to show/hide these existing features from the PCA menus.
And no, hacking the ASP code is a seriously bad idea - many of the pages are "sub pages" used by both the SA and PCA and hacking one can easily damage the other. Clearly TAC will have nothing to do with supporting your web clients if you go about doing this.
