I'm confused. Are you making a multiplayer mission with only one player in it or a true single player mission? (If the latter why is this thread called multiplayer death cam?)
If you're making a singleplayer mission you just need to override the default event script onPlayerKilled.sqs with your own. Note that you cannot look around freely and have the "Retry", "End" dialog on the screen at the same time. You need to decide at what point to display the "Retry" dialog bars because the player will have no way of exiting the mission until it is shown and no way to move the camera after it is shown.
Here is an example single player script, it needs to be named onPlayerKilled.sqs and placed in your mission folder:
It gives the player control of a seagull for 10 seconds to have a look around then displays the Retry dialog which prevents further camera movement. Alternatively you can use switchcamera to get the view of another unit (e.g for a first person kill cam). Or create a standard camera object and give manual control of its position (camcommand "manual on").
_unit = _this select 0
_killer = _this select 1
_pos = getpos _unit
_seagull = "seagull" camcreate _pos
_camera = "camera" camCreate [0,0,0]
_camera cameraEffect ["internal","back"]
_camera camSetTarget _unit
_camera camSetRelPos [2.71,19.55,12.94]
_camera camCommit 0
_camera camSetTarget _seagull
_camera camSetRelPos [-6.66,18.99,2.59]
_camera camSetFOV 0.700
_camera camCommit 3
_camera camSetRelPos [1.17,-21.71,-1.07]
_camera camSetFOV 0.070
_camera camCommit 3
_seagull switchCamera "external"
_seagull cameraEffect ["terminate","back"]
_seagull camCommit 0
_seagull camcommand "manual on"
In multiplayer the situation is different depending on the type of respawn you have selected in description.ext. onPlayerKilled.sqs is executed if you die permanently (respawn = "NONE"/0), onPlayerRespawnAsSeagull.sqs for seagull mode (respawn = "BIRD"/1) or onPlayerRespawnAsOtherUnit.sqs when you spawn into a teammate (respawn = "GROUP"/4). For unlimited respawning modes ("INSTANT"/2 or "BASE"/3) no script will be executed, instead you need to use a killed eventhandler to detect the player's death which performs whatever camera manipulations you want (usually during the respawnDelay period) before terminating back to the respawned player unit.