Maybe, try get permission from the authors of Calibri and if permitted use one of the font editors such as Macromedia Fontographer and convert it to the format you want.

Hey Vinz, you probably should try search google for font creators such as Macromedia Fontographer, FontLab or FontExpert and go to their home pages to find out more. Illustrator is good for you to use when creating you original designs but use these font creators to convert them into required font formats such as ttf etc..