Tikka addressed this question under the FAQ section on their website at one point. The answer was that there wasn't a torque spec for the action screws, just keep them "tight".
I'm a firm believer in consistency and believe in torque spec(s), but I trust what they say since they make them... not just distribute them like their owner (Beretta)
I own three T3's right now, all stainless Lite models in 6.5x55, .30-06 and .338 win mag. I've taken the stocks off all three after they were sighted in and "tightened" (not torqued) the screws during reassembly without any issue. There may have been a slight shift in impact but nothing horrid or opening of groups.
Maybe I just got lucky with mine and maybe there really is a torque spec, but I think you can do far worse by under tightening or over tightening than just keeping them "tight".