I am trying to figure out how to get to base58 as well and am a bit confused. I have read a few implementations on going to base58 from current apps such as https://github.com/pointbiz/bitaddress.org and the one posted on the bitcoin.it site and they all seem to take the value needing to change and convert it to a big integer. Then divide it by 58 and the integer is converted to base58 with the remainder going through the process again. Well looking at https://en.bitcoin.it/wiki/Wallet_import_format I understand the first 6 steps, but if I take number 6 and convert it to a base 10 number it's an insanely massive number. Trying to divide that by 58 would equal a massive number so that is where I am getting confused.

Example: step 6 = 800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D507A5B8D

to decimal ~= 6368099731808814328175274076776670756354696346421856450745089246076352148867543 0192536461

/58 ~= 1.09794822962220936692677139254770185454391316317618214668018780104764692221854 1899871318293103448275862068965517241... × 10^87

I assume I am going about this the wrong way.