I found this fantastic solution for this problem.

http://www.vbforums.com/showthread.php?t=435070

Lets say you call the parameter "test" you would use code like this

MyRpt.SetParameterValue("test", "HELLO" & Environment.NewLine & "WORLD")

where MyRpt is the variable of your report object..

Works like a charm for me so i thought of posting if anyone needs it.

Thanks.