You should have the option to do it via email, give that a shot
To activate manually using e-mail just perform the followin steps:
--From the LANDesk Management Gateway console, click Activation and Click Install activation
--A PGP-encoded text file (ldmg_activation.req) appears. This is the file required for activation.
--Click Save activation request to save the file.
--Save the ldmg_activation.req file to your hard drive.
--Attach the ldmg_activation.req file to an e-mail message and send it to firstname.lastname@example.org.