If you got the old one off, that's 90% of the battle.
Depends on how you remove it.
Cutting the legs from the package (assumes it's not leg-less such as BGA or MLF packaging) for example will do so without the need for heat until you go to desolder the legs. Most of it seems done before ever trying to remove the legs from the pads. Now imagine that too much heat is being wicked away by a ground plane, but enough is applied to the pad long enough that the pads lift off.
GO to Radio Shack and drop $10 on a tiny, super cheapie solder gun.
Not recommended as there's no heat control at all. Too much risk of damaging the board or components, especially with SMD parts.
For proper soldering, you either want a proper temp controlled iron or RF based design (Curie Point, such as Metcal/OKi). These types tend to be better at thermal recovery when using the correct tip for the job vs. a firestick (stick irons earned this nickname for a reason
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).
I do get the point of one time use, but if the OP knows someone with a proper iron, they'd be better off letting that person do it.
And if they're interested in working with electronics on a regular basis, invest in a decent iron to begin with (no need to break the bank to do this in the US). Hakko FX-888 is $80.27 on amazon, and includes free shipping.
My reasoning for mentioning this, is that the OP already has a hot air station.
Point is to have a fine point.
Worst tip geometry out there. Proper chisel geometry to fit the pad size is far superior (better for transferring the heat to the joint).
Grab some super fine solder while you are at it. The Pb free stuff is better for environment but requires more BTUs to melt so get the gold old deadly stuff if you want to make your life easier.
Yes on the diameter recommendation (0.15" - 0.02"). And Yes, lead free does require more heat (one of the reasons getting the existing part off has been a challenge).
The logic behind ROHS is crap. It's not more dangerous to the user, nor does it release the lead as they reasoned (that would be a battery that's using nothing but lead for the plates, not an alloy, which is what leaded solder is, typically 60/40 or 63/37).
Fancy reflow stuff is nice, but $12 at RS is money well spent.
For a one time use, OK. For regular use, not in the least is this correct. Too much risk of damage to the boards, components, and operator (burns), even with a skilled operator.