One would think that going from 44.1 to 88.2 could be done by just repeating each sample, or making a average between two samples. Going the other way you would think that you could just drop every other sample, or average each two samples to make the results.
However, I don't think you would like the results.
Read Dan's paper on sampling. You have to treat each sample as a sinc function, then add up the contributions from the sinc functions of several samples on each side to figure out what your new value should be.
Once you have a SRC program that does things right, making it take care of non related in and out rates, shouldn't be that much harder.