Re: Is there any way to go from 6.1 (10B141) to 6.1.2 (10B146) on an iPhone 4S without going to 6.1.
If you download it, it will start the install from what I understand.
The best thing to do if you want a jailbroken iOS is to simply not upgrade. Don't download the upgrades. Just don't do it.
When jailbreaking tools come out, they are for the current iOS. You can take the "current" evasi0n tool as an example. They found exploits to jailbreak 6.0.x. They held onto those as they knew 6.1 was releasing soon. That way, it'd be more unlikely Apple would patch those exploits. When 6.1 came out, they released the tool that worked on both 6.0.x and 6.1. As the first two updates to 6.1 came out, they updated the tool to work on those as well.
In the time leading to the release, they gave information on twitter and their site letting potential jailbreakers know which versions of iOS would work with their tool. That provided you with a "window" to upgrade to the newer iOS or remain with the one you were on. Had Apple patched the exploits in 6.1, the jailbreak would have been released to work with 6.0.x. In that case, downloading the upgrade wasn't useful until evad3rs let everyone know 6.1 would also work.
Also, you bring up "download it to your phone" which suggests you're looking at the OTA update option. If you want to jailbreak, get out of that habit now. You'll want to update iOS via iTunes and a computer rather than OTA. Things tend to work better for jailbreakers that way. The OTA update will allow jailbreaking, but you'll lose some other functionality. As an example, downgrading in the past hasn't be available to OTA updated phones in some cases.
If you're currently on 6.1, there's no real need to go to 6.1.3. 6.1 will jailbreak with the tool found at
evasi0n iOS 6.x Jailbreak - official website of the evad3rs while 6.1.3 will not.