On iSeries / AS400 servers the executables for Crossware Mail Signature are contained within the Library XWARE.
As part of the installation process, two links are created to these programs in /QIBM/UserData/Lotus/Notes/
To check that these links have been created, issue the following command:
"wrklnk obj('/qibm/userdata/lotus/notes')"
Select option 5 "Display"
This should show the libsig and the esig links