Accessing modx object from a subdomain ... possible?

I’m in the process of implementing Interspire Shopping Cart for a client whose primary site runs on modx evo. The cart’s home is at store.example.com, and the modx site is at www.example.com. I’ve successfully hooked into the modx object from within modx before (e.g., when creating custom modules), but am uncertain of how (or if it’s even possible/practical/safe) to access it from outside the system. Ideally, I’d have Wayfinder build the navigation menu for the shopping cart and perhaps run other snippets as needed to replicate the original template. I tried, but had a heck of a time with scoping issues. Any advice on tackling this?

In the meantime I’ve written a class within the cart that accesses the modx db (not via dbapi) and does bare-bones what I need to build the menu ... but it’d be helpful to gather opinion on what to do in a cross-database, cross-domain environment.

Thanks for your thoughts!