First, you will not get only the isomer you desire, because AFAIK, the allyl chloride or bromide will also alkylate ortho to the methylenedioxy structure.
Second, using normal friedel-crafts methods will generate HBr acid, which will tend to add across the allyl double bond, and possible cause multiple alkylations and polymerization. There are ways around this:
Post 468541 (missing)
(ning: "high-yielding OTC allylation of aromatics, anyone?", Chemistry Discourse) scrubs up HX with supported K2CO3
Post 515205
(psyloxy: "TsOH - best Friedel-Crafts catalyst ever ?!", Novel Discourse) uses tosic acid to catalyze the magical alkylation
anyhow, it's not so easy as it seems.