It'll be an option for the webmaster if that feature exists at all.
No encoding of your ID needed that I can see, though, just let you
use either any of the below URLs, whichever you choose.
This is easy enough:
http://domain.com/hosted/index.html?nads=chopsshit
http://domain.com/hosted/?nads=chopsshit
http://domain.com/hosted/index.html/nads=chopsshit
http://domain.com/hosted/nads=chopsshit
http://domain.com/hosted/index.html/nadsEQchopsshit
http://domain.com/hosted/nadsEQchopsshit

Chop would probably want to use this version:
http://domain.com/hosted/index.html/nadsEQchopsshit

As far as on hosted promos, all that foreign characters like "EQ" needs to be left out.

E and Q are foreign characters? So what, no letters allowed?

If my affiliate id is 'chopsshit', yes the 'EQ' is foreign to my affiliate ID.
Now if the "EQ' is static, it is not a problem to do gnats=EQ%affcode%.

I fully understand the "QMYDPHPRDX" in StrongBox, but that kind of bullshit has no purpose in passing affiliate ids on promo stuff. If affiliate ids are top secret, then I might be the second most trusted person in this biz.

Ah, yeah, the EQ is static. These are equalivent:
http://domain.com/hosted/nads=chopsshit
http://domain.com/hosted/nadsEQchopsshit

EQ means =

:D The equal sign will work just fine for old Chop. Only have to hit one key.