I'm not sure if you've tried to create a mambot to do what you need, but if you haven't, then you can still achieve this by hacking two-lines in components/com_content/content.html.php
...And as always, backup your file and document your changes
To begin, find this line of code (there will be two instances of it)
[code:1]$link_on = sefRelToAbs("index.php?option=com_registration&task=register"«»);
[/code:1]
Once you've found these lines, simply replace [code:1]com_registration&task=register[/code:1]
with
[code:1]com_comprofiler&task=registers[/code:1]
It's a gritty and unattractive workaround but it get's the job done. If you managed to construct a mambot to do this, I'd like to know so I too can avoid having to hard-code this solution.