Without disasembling is tough! But doable!!
Go to your LFS, & buy one of those ENOURMOUS nets. They are like easily 6-8 inches across. (They are only like 3 or 4 bucks)
Also, if your tank is set up for it, a nice divider wouldn't hurt. (That way you keep him on one side of the tank instead of him going back & forth frantically)
And with that big net & some patience, you will have him in no time!! =) 2 nets actually wouldn't hurt--one for each hand & to cover his next escape route! lol....
Good luck!