Check to see how many wires are in the wire that goes to your current outlet. If there are four then you are in luck. RED/Green to line one and Yellow/Black to line two. Get a new outlet with a line one and two (two holes) at radio shack and wire according to the color codes inside. You probably need to hook a high quality, outside grade phone wire to the new block or connections outside to tie into your current inside terminal block, probably inside your house, somewhere near where the exterior block is.
If your wire at your final location is only a two conductor wire then you should probably run a new 4 or 6 conductor phone wire to the location and install a new surface mounted outlet. This stuff is all cheap and they can talk you though it at radio shack. For my line 2 I always connect a new, high quality exterior grade phone wire all the way directly to the exterior block. This way you don't risk getting any noise or interferance from your pre-existing interior phone wiring. This way you can maintain the fastest possible dial up speed with fewer dropped connections because of old wiring issues. So, actually what I would do is leave your current setup for your phone and run a new wire all the way directly to your exterior block to minimize line noise for your internet connection. Be advised that for some reason computer modems always want the inner two pins on a two-line, four wire phone connector. So, if you try to wire one standard outlet for four pin, two line phone then your computer will always grab line one, ie: the middle red/green pair. This is why I always get a double hole outlet and wire the line two female with yellow/black onto the red/green terminals. You should also invest in a phone line polarity tester, pretty cheap at radio shack. This little dongle lights green if your wires are correct and red if you have the pair flipped to the wrong pin.