In this case, multiclassing into Druid with Initiate of the Old Faith (PH2) would probably be good enough. You get the druid's wild shape power and you can use a druid at-will attack power that has the Beast Form keyword once per encounter. At higher levels, you can use power swap feats to exchange one encounter, one utility and one daily power for appropriate druid Beast Form powers.
An alternative that would require more work but which might allow you to get closer to your idea of what a werebear PC should be like would be to homebrew a multiclass-only Werebear class. The initial multiclass feat might provide an at-will claw attack, and you could develop specific werebear encounter, daily and utility powers that could be obtained with power swap feats.