IDL 7.1.1 is available for use on all IRTF workstations.
There are 4 floating network licenses at the summit. This should provide ample IDL license for your observing and daytime needs.
There are also licenses available in Hilo and Manoa.
The astronomy package is available.
The SpexTool package is available.
Duke runs the license manager software. It is authorized with 4 floating network licenses. The installation number is 102255-2.
IDL requires the following is enviroment definitions:
setenv IDL_DIR /usr/local/rsi/idl
setenv IDL_PATH \+$IDL_DIR/lib:\+$IDL_DIR/examples:\+$IDL_DIR/astron:\+$HOME/idl
setenv IDL_PATH +/usr/local/Spextool:$IDL_PATH
alias idl /usr/local/bin/idl