The lap steel guitar is a staple of old school country and western swing. To properly imitate a lap steel guitar, we must first understand its limitations and strengths. Remember, a lap steel player can only really grab what notes are underneath the slide bar. The classic lap steel guitar tuning is C6 (low-to-high: C - E - G - A - C - E). Lets break it apart. On the bottom three strings you have a root position major triad (C - E - G). On the top three string we have a root position minor triad (A - C - E). Both of these triads are up for grabs on the guitar.
Here's an example of mixing root position major and minor triads. We will also slide into the chords as much as possible to get that steel sound. Download Audio Example... 
If we look at the C6 tuning we have the G and A right next to each other. This major second rub between the fifth and sixth degrees of the scale is very identifiable with the C6 tuning. This alone is not always the most pleasant sound.
In most cases a steel player will either include the C string above or the E underneath. This creates a really pretty tone cluster built by combining a major second and a minor third (G–A–C or E–G–A). Download Audio Example...
Now let's step back and keep in mind the tuning is just a major 6th chord. No big deal right? Here are the major 6th chord inversions on the top four strings. Download Audio Example...
Now by walking any one of these inversions down a whole step chromatically we can turn them into ninth chords. Download Audio Example...
Since a steel play primarily uses three fingers to grab chords and doesn't really strum, getting four notes at a time can be cumbersome. Here's a solo over a simple progression that puts it altogether. Download Audio Example...
Really try to be creative and comfortable within the rules we have set up. Then, don't fret and let anything be up for grabs.
