Its not too bad. You have to know how to do two things- solder and read simple schematic diagrams. Speaker level crossovers are a good soldering begineer's project since the leads are large, there is lots of open space and the components are heat tolerant. Some kit sellers will assemble the crossover for you for a pretty nominal charge. ACI for one does this.
I just finished 4 sets of xovers for the kit81's. Make sure you have some "thicker" solder, as some of the connections really soak it up. I found that flux really makes the solder flow onto the wire, espescially the 14 ga wire that these had, much better. And hope you have a good strong solder iron that generates good heat, not one of those 5 watt pencils. I used a mini torch for some of the larger connections (2 14 ga wire with 2 16 ga inductors with a capacitor).