i would just buy a skimmer, there are some cheap ones out there that work great. i tried making my own and ended up spending just as much as a bought one.
are you going to drill your ten? if so, i have before and the glass is really thin on the tens and is very very fragile. i cracked a few of them. if your not going to drill it then the money you spend to make an overflow box will be more then just buying one.
the reason i am saying all this is cause i went throught it already and triing to save you the time, effort and money.