It is possible to call DLLs from LabVIEW using the Call Library node. Call Library works best with a DLL that expects basic, C-friendly datatypes. Depending on the API, if you only need to call a few functions, this approach will probably not be too hard.
Maybe someone has already created VI wrappers for the Dallas DLL and will respond to this thread. You might try asking Dallas directly - they may know of someone or may have done it themselves. A quick search of their website yielded at least one LabVIEW app note (albeit for a different device than the one you're using), so at least they have some knowledge/awareness of LabVIEW.
Steven H.