If your manager is the contact you have given INZ to talk to about your work, then you MAY POSSIBLY get away with going through the residence application. I can't help thinking that one way or another, it still could leak through to HR etc. somehow, though.
But you certainly can't go for WTR without being sponsored by the company, with an official form to be filled in, not like the reference and role/responsibilities letter that the manager could give you. WTR is a different kind of temporary work visa - you don't HAVE to go through that on the way to getting Residence.