I got a retweet from someone that a Chicago radio station is saying the Hawks can cure their cap problems by retroactively placing players (e.g. Hossa, Johnsson, Campbell) on LTIR. There are a couple of things wrong with this idea. Let's start with the big one.
WHEN A PLAYER GOES ON LTIR, HIS CAP HIT STAYS.
50.10 Player Injuries, Illnesses and Suspensions. (a) All Player Salary and Bonuses paid to Players on an NHL Active Roster, Injured Reserve or Non Roster that are Unfit to Play – being either injured or suffering from an illness – shall be counted against a Club's Upper Limit, Actual Club Salary and Averaged Club Salary, as well as against the Players' Share.
The only cap relief for LTIR allowed by the CBA is that a club is allowed to acquire a replacement player, and is allowed to exceed the cap by up to the amount of the injured player's cap hit in order to do this, provided that the injured player cannot be reactivated until cap room is made for him. This is not the same as having a player's cap hit reduced. The CBA simply allows the team to exceed the cap limit while the player is on LTIR.
So, even if this retroactive gambit were allowed, it wouldn't help.
And it's not allowed.
16.11 Injured Reserve List.
(e) Any determination that a Player is eligible to be placed on the Injured Reserve List, or designated as Injured Non-Roster, shall be made by the Club's physician in accordance with the Club's medical standards and documented by a verification signed by the Club physician and countersigned by a Club executive and by the Player in the form attached to this Agreement as Exhibit 28. Such form must be faxed to and received by Central Registry, and faxed to the NHLPA, all in accordance with Exhibit 3, prior to the Player being added to the Injured Reserve List. [...]
(g) [...] The Club must notify Central Registry, in accordance with Exhibit 3, of its intent to activate the Player prior to the Player playing in an NHL Game by way of a verification signed by the Club physician, and countersigned by a Club executive and the Player, attached as Exhibit 25(C). This form must be faxed to and received by the Central Registry, in accordance with Exhibit 3, and a copy faxed to the NHLPA, in accordance with Exhibit 3, on the day the Club activates the Player to play and, upon Central Registry's receipt of such verification, the Player will be officially removed from the Injured Reserve List.
50.10 (d) (i) A Club seeking to exercise the Bona-Fide Long-Term Injury/Illness Exception must simultaneously so notify Central Registry and the NHLPA, in writing, before any Player replacing an unfit-to-play Player shall be permitted to play with the Club; (ii) The Player Salary and Bonuses of the Player that has been deemed unfit-to-play shall continue to be counted toward the Club's Averaged Club Salary as well as count against the Players' Share during the League Year in which the Player is deemed unfit-toplay (including during the period such unfit-to-play Player is on a Bona Fide Long-Term Injury/Illness Exception Conditioning Loan to another league).
Short version: you can't do it and it wouldn't help you if you could.