@veezh: Tweak the bearings for that character in a font editor, maybe? (Fontforge :P).
@flandroid: Yep, converting PS OTF fonts is a pain. You can try to port the hinting instructions by copying the PS Private table over to your converted font, and a run of AutoHint & AutoInstr on Fontforge, but it's far from perfect...
Or, to build generic hinting instructions via FontForge (from a completely non hinted font [if not, Clear Hints & Clear Instr beforehand]).
* Add & let guess the BlueValues & OtherBlues settings in the PS private table.
* Add & let guess StdHW, StdVW, StemSnapH, StemSnapV in the PS private table.
* AutoHint (again)
But it really depends on the fonts, and sometimes, you'll end up with something far worse than the unhinted font
Or you can just use the OpenType CFF font directly, without forgetting to make it a .ttf and not a .otf
If you're still unsatisifed with the hinting, you can try to AutoHint it *as a CFF font*, and not a TrueType font. (Same as before, clear hints & instrs, Fill & Guess the PS private table, AutoHint, export as OpenType CFF). That usually works better, FontForge handles PS fonts way better than trueType ones