Other than through AMD overdrive I am not sure. It has limits to what you can do but it seems you can get good little performance increases out of both very easily. I wouldn't personally overclock the cpu with overdrive unless you have an unlocked multiplier which i dont think your cpu does. But as far as the card goes, overdrive is free and easy.Overclocking - Power - Temp - AMD ATI Radeon HD 5770 and HD 5750 Review | [H]ard|OCP
You can also check out this review for your cpu. Might give you an idea of what you can expect.| [H]ard|OCP]AMD Athlon II X4 620 Quad Core Processor Review - Overclockers Club
I wish I could write you out a step by step guide but im not the person you would want to do that. Im sure someone will chime in at some point and give you some more info. It seems like this place slows down on the weekends. Everyone away from the work computers lol.
I can tell you that what you will need to do is raise your core a.k.a reference clock and adjust voltage accordingly. Overclocking a cpu with a locked multiplier is a bit more complicated than with unlocked. I was able to hit 3.817ghz without touching anything but the cpu multiplier. Best of luck and enjoy yourself, pushing the limits of silicone can be a blast.