Its ugly in that you have to tweak each computer, but you can try a cutom paper size. I usually create an additional printer pointing to the same local or network printer but with a different name. Then modify the properties of that printer to change the user defined paper size. Specify that printer in your label form and it will print single labels. For instance if you have a Panasonic 1124:

Create new printer called Labels (using the Panasonic driver)
Modify user defined paper size of Labels to be 350 hundreths of an inch by 100 (this is 1" by 3.5")

in code:
set printer to name labels
label form yourlabel to print next 1
set printer to default