I could not find torque specs on the DISA in Bentley...but if the screws are loose, tighten them evenly by feel...it's not 'mad' tight. Also, as others have learned too late, use the right size bit. I remember a guy who stripped his bolt...he used an allen bit that fit...but it was a torx head screw! I'm 'vaguely' remembering T25...but don't trust me!
If you search torque values or something...I bet that posting with a TIS on all torque values will come up...hope so...but think you're going to do it by feel anyway...so my guess would be somewhere between 10-20 lbs...but don't go crazy!