serial parametric strings

Hello, I'm new to arduino. I need to know if there's already a library or whatever to do the following:

I want to receive a string from which I will take several variables. I'll explain in an example:

I receive "27469384" that means 3 variables: var1: 27 (integer) var2: 469 (integer) var3: 384 (integer)

the variable map would be: 11222333

It should be taken in consideration that I will receive constantly 20 of these strings per second, while doing other calculations, so it must be Interrupt driven.

The target board I got is an Arduino MEGA 256

PD: I already did this in a PIC32 (microchip 80Mhz 32-bit microcontroller) but limited to only 5 pwm's. The serial thing i did it Interrupt driven over DMA's. Actually it can easily receive strings (of 22 chars each) 100 times per second while doing floating point math and other heavy calculations at the "same time", while other timer based processes also run in backround. I don't know if the arduino microprocesor has the balls to do this (i mean computation power), but I must start with the basics which is communications.

Originally it was OK, but as proyect grew, needed more PWM that PIC32 doesn't have.

thx 4 ur time :)

Cross-posting is frowned on here. Please don't do it.

I don't think there is a library to do that.