First, it's unlikely he'll dress. At center there is T. Ruutu, S. Koivu, N. Kapanen and Jokinen (in no particular order) ahead of him, and even if one of them plays wing, Eloranta or more likely Hahl can play center too.
Second, if he does, it'll be as a fourth line center. I think Summanen was looking for someone big, mobile, solid defencively and good on face-offs. Viuhkola doesn't fit, and for that role I'd take Koivu ahead of Immonen. Other options (Pakaslahti, Helminen, or even Kuki) lack speed.