It's possible, but you should note that Windows limits the number of actual downloads running simultaneously to 2 (or might be 3).
If you're the one that's downloading, there's nothing you can do to request more than what that person is offering.

Downloading/installing mutliple request addons can have a deleterious effect.

As a final point for this, from me, I must point out, that mIRC is not a filesharing program, and that filesharing is not supported on these forums.