OK, forget the "::" thing. I've switched to <templatelink>, like this:
<templatelink>test|param1=value1|param2=value2</templatelink>
To give the link a name different from the template (in this case, "Test"), use multiple lines:
<templatelink> test|param1=value1|param2=value2 Click on this! </templatelink>
Leading and ending newlines are ignored. First line is the template, last line is the link title, everything in between is currently ignored.
This should be clean enough, syntax-wise.
Cheers, Magnus