Oh, I saw this sooo late... Anyway, for the record.
By 4-way you mean the ministick right? Well:
1) You have to set the X and Y axis as bands by right clicking them and selecting "bands"
2) By default, my SST software divided them in 3, but if yours doesn't, just click Edit Bands and then click somewhere to create a new one.
3) Simply assign the arrow keys to the "top" and "bottom" bands, so you end up with an X axis with three bands: one is Left-Arrow, one is empty, and the other is Right-Arrow.