Kevin,
You will need to do some pre-processing of the text in the text box. Firstly is stID always going to be part of what is pasted into the text box? If so that needs to be stripped out. I notice that your codes are a constant 11 characters long is this always the case? You would use the following functions to manipulate the text.
dim s,r,c as String
dim n as Integer
Let s = "StIDWC0000-0000WC0000-0001XX0022-0022"
[TABLE="class: grid"]Len(string)Gives you the length of the stringlet n = len(s)
Right(string,length)Returns the string from the rightlet r = Right(s,n-4)Mid(String,start,length)Returns the string starting at startlet c= Mid(r, 1, 11)
[/TABLE]
So having stripped off "stid", determined the length of the string, divide that by 11 and this is the number of codes entered. Step through your string returning each code and you can build up your full query string into [StID] IN ('WC0000-0000','WC0001-0001','XX0022-0022')
If you are not that familiar with string manipulation in VBA then a quick search of the internet will help.
Duncan