If you screw up with amateur tuning your car will be off the road for a whole lot longer than a day or so at the tuners..
Basically, you need a wideband O2 sensor to make sure you don't lean it out too far and some sort of knock sensor to ensure you don't wind too much timing in.
Then, you're going to need lots of "private" road to tune on and it's going to take you a long time to find enough different conditions to hit every cell.
Oh, and you'd best learn the software pretty well before you start as like I said above, it's VERY easy to ACCIDENTALLY f**k something up and NOT NOTICE that you have f**ked it up until you melt a piston.