Using Scott Klement's HTTPAPI

I am trying to set up a software vendor's product, which incorporates and uses Scott Klement's HTTPAPI Service program, on a v5r1 system.
It's using HTTPAPI to prepare and send XML docs and consume a web service.

However, in doing so, HTTPAPI apparently needs to use the Digital Certificate Management facilities of the OS. On v5r4 this is no problem as DCM is part of the OS.
On v5r1 it is a separate OS option (34). So, we installed that option. However, it also somehow needs 5722-AC3 (Crypto Access provider 128 bit), which was rolled into the base OS on v5r4
but is a separately ordered and licensed product back on v5r1. The client doesn't have the 5722-AC3 on its install CD's and they have no way of getting it, as far as I know.
Without 5722-AC3 we can't set up the Certificate Store on the v5r1 box. (It says it needs 5722-AC3 installed).

It occurred to me that I could comment out the DC requests and see if the HTTPAPI would still work (in other words, make the API not attempot to use DC's).
I inquired of the vendor what would happen on the web service end if I did this and they don't know.
Apparently, we both have levels of ignorance about Digital Certificates.

So, I guess I'm asking if anyone has tried this and whether I am barking up an empty tree (maybe DC is an integral part of XML conversations with web services?)

Can anyone direct me what procedure calls in HTTPAPI can/need to be commented out?

BTW, the software vendor only supports their application from v5r4 but agreed to let us try to retro it to v5r1 for a mutual client.

Thanks for any advice, and be gentle with me, acknowledging my ignorance of what I speak.