This report shows that brown dwarfs could be up to nearly 1/10th of a solar mass:

Massive Object Calls Planet Discoveries into Question.
By Robert Roy Britt
Senior Science Writer
posted: 19 January, 2004
1:05 p.m. ET
http://www.space.com/scienceastronomy/heavy_objects_050119.html

Then the speed needed would be only 1/100th of what you mentioned.
Actually, it might even be possible if the planet was only at 10 Jovian masses, 1/100th a solar mass. A rough estimate for the speed V of the planet on impact can be obtained from the equation mV^2/2 = GMm/R, so V = sqrt(2GM/R), M the star mass, m the planet mass, R the radial distance, G the gravitational constant, G = 6.67 x 10^(-11) m^3/s^2 x kg.
If the planet maintained its size until impact at about the radial size of Jupiter, then the distance R would be about 1.4x10^8 meters. With a neutron star mass of one solar mass, M = 2x10^30 kg, V = 1400 km/sec. However, it is likely that the planet will pass through the Roche limit of the star, where the planet will begin to break up. Then the radial distance could be on the order of the size of the neutron star 10 to 30 km. Using a radial distance of 20 km, V = 110,000 km/sec.
So for a planet at 10 Jovian masses, 1/100th of a solar mass, this could result in a velocity imparted to the star of 1100 km/sec, within the order of magnitude of the velocities observed for the neutron star kicks in general and close to that for this extreme case.

We discussed on this forum before what would happen by momentum conservation if the mass of the planet was completely captured by the star with no mass thrown back up. The conclusion was that the star would remain where it had been before.
But of course this is not likely to be what happens. In the case of the Shoemaker-Levy impact to Jupiter a tremendous amount of mass was thrown back up. This also is what happened in the case of the planetary impact to Earth that created the Moon. Then in this case the star would be sent back in the reverse direction.
Another possibility is that at the tremendous, relativistic speeds the planets mass would be traveling at, it could pass right through the stars gaseous body. In this case as well the star would continue on in the opposite direction:

Space Sciences
re: I'm afraid these guys are right, Robert.
Posted by Robert Clark on 9/10/2007 5:28:44 PM
http://www.habitablezone.com/space/messages/481643.html

There is also the possibility that the tremendous pressures produced by the impact at relativistic velocity could produce thermonuclear explosions that would also propel the star backwards.

Bob Clark