I actually use lint-free chamois fiber optic swabs. They are on a firm but flexible plastic base, and work incredibly well with fiber optic cleaner (which is basically 99+% isopropyl alcohol). They're on the pricey side, so I use Qtips to get the bulk, then then use a couple of these at the end to remove all traces of the old AS5, lint, oil, and anything else from the CPU and HSF.
I did an experiment and was amazed that after cleaning until a fresh (isopropyl dipped) Qtip stayed pure white after a firm rubbing, that the chamois swap got almost black with just a few swipes back and forth. If anyone is interested ask and I'll go find the bag and post the specifics.