Formally, what you're really looking for is a key derivation function (KDF).
The Crypto++ API includes a PasswordBasedKeyDerivationFunction class, but that doesn't really seem optimal for your purposes; since you already have a high-entropy random seed, what you really want is a simple key-based KDF, not a fancy key-stretching KDF meant for use with passwords.
Fortunately, it's not hard to implement one yourself. A very simple approach would be to use your "seed" as the key for a stream cipher (or to, say, AES in CTR mode), and use the keystream (which you can obtain by encrypting a bunch of null bytes) as your source of random bytes.
(You can then convert these random bytes into uniform random integers in your desired range e.g. by rejection sampling: to generate a random number between $0$ and $m$ inclusive, first find $k = \lceil\log_2m\rceil$, i.e. the length of $m$ in bits, then generate a random $k$-bit string. If this bitstring, interpreted as a binary number, is less than or equal to $m$, you're done; else, toss it out and repeat. It's not hard to prove that, on average, you'll end up rejecting less than half of all bitstrings (since $m \ge \frac12 2^k$). Note, however, that this does potentially leak some statistical timing information about the most significant bits of $m$, which might matter if you want to keep it secret.)
Alternatively, with only slightly more work, you can implement a standard construction like HKDF (RFC 5869), or one of the DRBG algorithms from NIST SP 800-90A (note: do not implement Dual_EC_DRBG!). CTR_DRBG, in particular, is very similar to the simple "use seed as key to AES-CTR, take keystream" suggestion above.