From what I could see, ActiveX automation and ActiveX contianers are not supported. Atleast then are not on the PDA palette. What makes it is a little more confusing is that the online help does not even mention ActiveX on the list of unsupported features.
The PDA can handle calls to dlls. The online help says:
You can use a Call Library Node to access external functions written in C. You must create a stub DLL on the host computer so you can place these nodes on the block diagram and configure them correctly. When you compile a PDA VI that uses C code, you must include the .c file in the Build PDA Application dialog box. LabVIEW compiles and links these files in the PDA VI. You also can include static libraries in the build, but the library must be no
more than 64 K for Palm OS devices.
If you pass large arrays to or from a Call Library Node, you might notice execution delays. You can avoid these execution delays by using a DLL function that partially updates the arrays.