PHB1 Druid doesn't have a companion. Sentinel Druid from HotFK does, but AFAIK there is no MC feat that gives access to its companion. You can Hybrid Sentinel (found in Dragon 400, this isn't yet in the Compendium). Your other options include MC Shaman, and that's pretty close to it. You could pick up the Animal Master theme or MC to an Arcane class and get a familiar. You could be a Ranger hybrid as well.
I'll just say, none of these are terribly potent options. Hybrid Sentinel might work OK, but I really don't know. I'll suspect stat synergy is low, but you could maybe do it with CON. Anyway, none of these look like great options.
I'd opt for a non-mechanical solution. See if you can get your DM to let you tame some sort of animal. It will be an NPC, but there are some types of animals you might get away with. Doesn't offer the same level of control as a class feature, and WILL count as a party member generally, but could be fun.
The other option would be to use HoS and rebuild your character as a Binder, but that will probably not turn out too great. In any case from what I can see at level 9 any warlock can use the Binder's summoning power. And that may be the best answer is to get a summons of some sort (Figurines of Wondrous Power are a possibility too).