Ikhwan, there are 2 lenses on IIc (but you already know that). One is 60mm (6cm) Focotar and other is either 95mm Focotar or 100mm V-Elmar or Focotar-II. If you have V-Elmar version, you can easily exchange it for Focomat-II (if you are able to find it). You can find more information here:
http://leica-users.org/v31/msg11354.html
There is German company which maintains some spare parts and upgrades Focomats:
http://www.kienzle-phototechnik.de/...IIc__Vall/leitz_focomat_ic_iia_iic__vall.html
They also can exchange the lens mounts to accept modern lenses, although it's quite expensive.
Contact them for more information.