Legit?

[Avodroc20]

{Gleam of Battle} is on the field, I choose {Boros Battleshaper} as my attacker, it gets a +1/+1. Correct? Then I use Boros' ability and choose Boros to not attack. Can I do that? I chose my attacker, it gets the counter, then I make him not attack. Sounds right to me. Correct me if I'm wrong.

Also, I have 3 of each card, if I'm wrong, is there anyway I can make it work that way?

[TreeTopSky]

No. At the beginning of each combat phase his ability triggers. At this time you are unable to select your attacking creatures untill his ability has been resolved.

(e.g. Goes to combat phase -> Ability activates -> You select which creature can/can't attack/block -> Select your creatures you wish to attack with )

[griffin131]

 {Maze of Ith} also.