We have no method to tie a particular discount code to a specific Affiliate; any discount code can be used by anyone at any time, although if you wish, you can create single-use Cart Discount codes that would be useless after being redeemed once.
If you were intending to use this as a sort of Affiliate-referral code -- i.e. so the Affiliate could just hand out a code, and buyers would enter that code in their cart to credit the Affiliate for that sale, with the discount being their incentive for entering the code -- for this purpose, it's just inherently unreliable to expect buyers would always remember to enter some code manually, discount incentive or not. However, we do have a better method to recommend for Affiliates who just want to hand out codes without posting links online anywhere.
Once the Affiliate joins your program and obtains their link code (or you can log into their E-junkie account to obtain the link code for them), you can get the href= URL out of their link code and provide that URL to a link-shortener forwarding service like tinyurl.com. This would give the affiliate a short, simple URL to hand out like tinyurl.com/a3c2b1 or even tinyurl.com/buy-from-bob (you can specify whatever you want after the "/" as long as it isn't taken already). If you don't like tinyurl, there's plenty of similar services available; just search Google for "link shortener" or "url shortener".
BTW, for simplicity's sake, we would recommend using our new Common Affiliate Settings (Admin > Affiliate Program Settings) rather than product-specific Affiliate settings, unless you really need to offer different percentage-share commissions for different products.