You can format your string with STUFF(). However, I wouldn't advice to convert your column. You should convert the GETDATE()-1 to string or even better, change the column data type to the correct one.
Here's an example of how to do it both ways.
SELECT CONVERT( datetime, STUFF(STUFF('201410011112', 11, 0, ':'), 9, 0, ' ')) StringToDate,
REPLACE( REPLACE( REPLACE( CONVERT( varchar( 16), GETDATE() - 1, 120), '-', ''), ' ', ''), ':', '') DateToString1,
CONVERT( char( 8), GETDATE() - 1, 112) + REPLACE( CONVERT( char( 5), GETDATE() - 1, 14), ':', '') DateToString2