Normally custom development of objects is done with objects that belong to a transportable package. Local development belongs to package $TMP. There's a simple way to change the package of any object using the following method.
Go to transaction SE03, then choose Change Object Directory Entries.
You then have to choose which kind of workflow related object you want to change.
Type SOBJ for changing business objects, PDWS for changing workflow templates and PDTS for standard tasks, or just use DEVC with value $TMP for changing any kind of local object.
In the next screen, find the object and double click it to change the package.