Do it in conjunction with a loop command and variables. Set it to run 900 frames (or whatever you want), then when it reaches 900 add 1 to a variable. Create this inside of a conditional branch that is constantly checking what that variable's value is. So if the value is equal to 2, then the timer has reached 1800 frames. If the value of the variable is 10, then the timer has reached 9000 frames. So if you want more frames used, change the conditional to check for a higher value, etc.
In VX, 60 frames = 1 second. So, 1 minute = 3600 frames, 10 minutes = 36000 frames. With this, let's pick 500 frames (for our example from above) and use that. If the value of our variable is 1, then 500 frames has passed. If the value of our variable is 72, then 36000 frames has passed. Therefore, you set the conditional branch to check when your variable is equal to 72, when this is true, your condition will occur. Don't forget though that when this condition is true, to reset the variable to 0 and turn the event off so that the timer stops.
Edit: Oh, you edited your message just before I posted this. lol