Something like this should work fine.
IDbCommand cmd = new SqlCommand();
StringBuilder sb = new StringBuilder();
sb.Append("insert into foo(col, col2, col3), values");
int parms = 0;
for(int i = 0 ; i<3; i++)
{
sb.AppendFormat("( @{0}, @{1}, @{2}),", parms, parms + 1, parms + 2);
cmd.Parameters.Add(new SqlParameter((parms++).ToString(), ""));
cmd.Parameters.Add(new SqlParameter((parms++).ToString(), ""));
cmd.Parameters.Add(new SqlParameter((parms++).ToString(), ""));
}
sb.Append(";");
cmd.Parameters;
cmd.CommandText = sb.ToString().Replace(",;", ";");