thanks both for the replys, in the end i pasted the data into a text file, created a parameter with the data type of 'DETextfile' and used that.
the toolbox i wanted to create was a select by attribute tool that could select thousands of features based on the list i pasted into the text file.
the tool works by reading the text file into a list and then looping through it in batch's of 10 lines and selects the features and then moves onto the next 10 lines and adds them to the already selected features.
thanks
Stu