I do not believe that the '94 Roadmaster had the identical wiring, such that the remote locking system would just plug and play - but (and I know this will sound like I'm being cute) I couldn't say without first looking.
What I can say is that you can buy a perfectly decent Chinese remote locking controller (lock, unlock, rear hatch open, blinks lights on lock/unlock) from Amazon for $16.99 (Ref:
https://www.amazon.com/gp/product/B07L4LTXSK/?tag=bbodyforum-20 ). You should have little trouble wiring it up by reference to the GM CC shop manual, and I rather suspect that, even where you have no remote locking, the wiring harness will be essentially the same. All wires needed should be present above the left rear wheel well, under the plastic cover.
If needs be, I may be able to provide a few pointers and scans of the wiring diagram for you (but, not today).