The right to which you speak can be found perhaps in a couple of places. In section 11 there is a right not to be compelled to give witness against oneself during a proceeding. There is potentially a section 7 right--fundamental principles of justice--that applies perhaps more broadly and includes that right.
The Supreme Court of Canada in R. v. Lyons in 1987, which was the first post-charter challenge of the dangerous offender provisions, said that section 11 rights don't apply per se to dangerous offender proceedings, again because of the context of that provision. They talk about rights that traditionally attach to trial and to charge. The decision of the court there was that in fact the rights that were claimed by that particular individual could not be used as a shield against the dangerous offender finding. So I don't think it would fall under that one.
They then turn to analysis of section 7, the fundamental principles of justice attaching to the right to life, liberty, and security of person. They said what was important in the dangerous offender proceedings was not to perhaps transfer over these rights one by one as they might apply, but in the context of the overall proceedings to ensure fairness, to ensure that the offender had an opportunity to present his side of the story, to make sure there was not an arbitrary hearing, etc. The important thing is that the offender's right to silence is in fact maintained in these proceedings. He does not have to get up on the stand.
Well prior to that phase, recall that there is an impartial psychiatric assessment ordered by the court, which is often the basis of most of the arguments during a dangerous offender application, and in most cases, as a matter of fact, through legal aid there are subsequent experts brought on board by defence to counter any negative assertions by the crown's impartial witness.