You can create a custom script (Tools > Distribution > Manage scripts) or even use a provisioning template but it is maybe overkill.
If you have a licence for Patch Manager, you could also create a custom definition and set up a rule to detect and apply the cert when needed and target only some scopes, then you activate autofix and you work is done.
But if you looking for a way to just select your pfx file and let LANDESK handle the deploy by itself, i'm not sure it is possible, some scripting is needed.
Got it. Thanks Cyril.