Help with Inverse Kinematics for 3 DOF Hexapod Robot

I am working on a 3 Degree of Freedom (DOF) hexapod robot. I am having trouble with Inverse Kinematic Equations. I tried several ways and haven't yet been successful in implementing IK into my leg calculations. It is also difficult in PICBasic because there are no inverse trig functions built in. I have been able to use ScaleRobotics's Atan function to calculate ACos but I am having trouble with the basic equations for finding the angles of the leg using leg placement. Ultimately I want to be able to send numbers like 3,2 and have the robot move forward by 3 and over by 2 diagonally from its starting position.

I was going on the thought of having 6 legs and moving one leg forward and the other 5 backward by calculating the change in x (or dx) and dividing it by 5 and calculating the change in y (or dy) and dividing it by 5 and then each time back the it adds dx to the current x and adds dy to the current y and then recalculates the angles for the new xcurrent and ycurrent values. I feel this would work but I am having trouble calculating the angles.