SSIS Script Task Concatenation Issue

Hi All

I am loading the data from Flat File to Sqlserver destination.In between I want implement below logic

COL1(String),COL2(datetime),COL3(string),COL4(string)

If COL3 SUBSTRING(COL3,1,2)="00" THEN

COL+COL2+COL3+"R"+SUBSTRING(COL4,2,3)

If COL3 SUBSTRING(COL3,1,3)="ABC" THEN

COL+COL2+COL3+"R"+SUBSTRING(COL4,2,3)

Otherwise:COL+COL2+COL3

col1=KK

COL2=2012-01-31:12:00:AM

col3=0045B

col4=5320

my desire output like below

kkJAN 31 2012 12:00AM0045BR32

how to implement above logic in script component

Thanks

CMK