STEP ONE: YOU WILL NEED A STEEL BAR of some kind, and you will need an EXTENSION NUT......an extension nut is a small piece of steel, which you put under the strings of your guitar to raise them up off the fret board.
they usually cost about five dollars, and they are available in lots of places, but paul beard's resophonic outfitters has them here...http://www.beardguitars.com/Pg8Resophonic%2012.html.....he also carries different types of steel bars. a cheap steven's bar is always a good start, but any bar will do
you just need to find what is most comfortable for your hands.....the bar can cost between 20 bucks and 75, depending on what you choose......many local music stores will carry these......here's a rugged looking picture of an old school extension nut as it should go on a right handed guitar
as it would look to you sitting in your lap

STEP TWO: DETUNE THE strings of your acoustic guitar......normally, you don't want to detune all the strings at once, because it can mess with the tension you put on the neck....the best way around this is to detune each string gradually. the best way to do this is to
buy one of those cheap plastic string winders. they are also about five bucks, and will save you a world of time.....start but giving your sixth string five or six turns. then go to your first string and detune it five or six turns. then the fifth, the second, the fourth and third.
in this way, you will gradually loosen all the strings together. repeat this process until the strings are loose enough that you can slide the nut extender under them.

STEP THREE: SLIDE THE NUT extender under the strings, up where the nut is on your guitar already, where the head stock meets the neck. slide the steel piece right over this, UNDER your strings. If the extension nut has a longer side, the longer side goes TOWARD
the head or to your RIGHT if you're playing right handed. the strings should then naturally fall in to each of the six grooves that are pre cut in the steel nut. 

STEP FOUR: RETUNE your guitar, following step two in reverse. in other words, tune each string a small amount, 6, 1, then 5, 2, then 3 and 4.....gradually keep working that pattern, until you get to pitch.
step four and a half:

TUNINGS.....i would recommend if you have a regular guitar acoustic guitar, you tune to OPEN FA C, FA C low to high. this is the EXACT SAME THING as G dobro tuning, or high bass G, the same scale steps, same intervals. the one three and five of the major chord, it's 
just a whole step(two frets lower).....the reason for this, is most acoustic guitars weren't made to handle the pressure of being tuned up that high, so if you go to a G, you may break strings. Open F gives you the same thing, just with a lot less tension on your guitar.
most dobro instruction is written in this tuning. so you can use any of the stacy phillips books, or most of the other instructional stuff you find out there, and it will work, you'll just be pitched a step low.

if you are a rebel and want to try another tuning, the most user friendly one for your acoustic is OPEN D which reads D A D F# A D , low to high. this is the same as open E tuning, only a whole step lower. this tuning is also great, but there is not as much lap style
instructional material written for it.....

SO there you have it! a cheap and easy way to try lap style guitar and see if you like it. .....when you want to return your guitar to it's 'normal ' state, simply detune using the above description, and slide the extension nut out, and retune.....

more information can be found here........

have fun...>!!!!!!!