The SAS DOC shows a much different list of arguments for the IRR function. So, with the transposed file, you need to list the individual SAS NUMERIC variables passed to the IRR function. Not sure where you got that a SAS CHARACTER variable would even be remotely suitable.
So, my suggestion would be to generate a SAS macro variable "set" listing the "1" to "n" variables for your DATA step assignment statement with the IRR function.
A SAS-maintained view SASHELP.VCOLUMN or DICTIONARY.COLUMNS can be used with either a DATA step or PROC SQL to generate the variable list as macro variables and use a SAS MACRO to build the assignment statement.
Check the SAS forums archives, or use the SAS support
http://support.sas.com/ website's SEARCH facility (or Google advanced search using arguments along with the parameter site:sas.com), to find related SAS technical/conference papers (example link below for a start) on using VCOLUMN and COLUMNS along with SAS code for your assignment statement.
Scott Barry
SBBWorks, Inc.
Creating Data Driven Programs with the Macro Language
Brian Varney, Trilogy Consulting, Kalamazoo, Michigan
http://www2.sas.com/proceedings/sugi24/Posters/p254-24.pdf