I know I can do it with one of those, however I think this is a feature that should be incorporated with the CB core. You can hack the CB file so that clinking the user list links requests a connection and block the profile altogether with one of those (I know, as this is what I have done on my site).
However this would really be an excelent core feature (and give a much desired feature whilst remaining true to Joomla's open source policies as these components cost and are all encoded, a quick search on Mikko's, which the other seem to be ripping off is an example of why this should be a core feature).
As I said I have this working on my site, but it really should be considered for incorporating into the CB core as a default feature (it would be nice to have a button to request friends in the list, but that is a bit beyond me, so I just hacked the link that is already in there to be the request link).